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  • #16
    Weekly U.S. Influenza Surveillance Report


    Key Updates for Week 4, ending January 25, 2020

    Key indicators that track flu activity remain high and, after falling during the first two weeks of the year, increased over the last two weeks. Indicators that track severity (hospitalizations and deaths) are not high at this point in the season. Viruses

    Clinical Labs
    The percentage of respiratory specimens testing positive for influenza at clinical laboratories increased from 25.7% last week to 27.7% this week.

    Public Health Labs
    Nationally, B/Victoria viruses are the predominant virus this season; however, during recent weeks, slightly more A(H1N1)pdm09 than B/Victoria viruses have been reported.

    Virus Characterization
    Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report. Illness

    Outpatient Illness: ILINet
    Visits to health care providers for influenza-like illness (ILI) increased from 5.1% last week to 5.7% this week. All regions remain above their baselines.

    Outpatient Illness: ILI Activity Map
    Flu Activity & Surveillance

    The number of jurisdictions experiencing high ILI activity increased from 37 last week to 44 this week.

    Geographic Spread
    Spread map week 4

    The number of jurisdictions reporting regional or widespread influenza activity increased to 51 this week. Severe Disease

    Hospitalizations
    The overall hospitalization rate for the season increased to 29.7 per 100,000. This is similar to what has been seen at this time during recent seasons.

    P&I Mortality
    The percentage of deaths attributed to pneumonia and influenza is 6.7%, below the epidemic threshold of 7.2%.

    Pediatric Deaths
    Fourteen new influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 68.

    All data are preliminary and may change as more reports are received.

    A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

    Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

    Key Points
    • Outpatient ILI and laboratory data remain elevated and increased again this week. Nationally and in some regions the proportion of influenza A(H1N1)pdm09 viruses compared to influenza B viruses is increasing.
    • Overall, hospitalization rates remain similar to what has been seen at this time during recent seasons, but rates among children and young adults are higher at this time than in recent seasons.
    • Pneumonia and influenza mortality has been low, but 68 influenza-associated deaths in children have been reported so far this season.
    • CDC estimates that so far this season there have been at least 19 million flu illnesses, 180,000 hospitalizations and 10,000 deaths from flu.
    • Flu vaccine effectiveness estimates are not available yet this season, but vaccination is always the best way to prevent flu and its potentially serious complications.
    • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.

    U.S. Virologic Surveillance

    Clinical Laboratories

    The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
    45,949 662,536
    12,715 (27.7%) 107,343 (16.2%)
    6,335 (49.8%) 40,123 (37.4%)
    6,380 (50.2%) 67,220 (62.6%)
    INFLUENZA Virus Isolated
    View Chart Data | View Full Screen Public Health Laboratories

    The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
    1,801 41,527
    1,129 21,184
    629 (55.7%) 9,738 (46.0%)
    585 (96.1%) 8,261 (87.5%)
    24 (3.9%) 1,175 (12.5%)
    20 302
    500 (44.3%) 11,445 (54.0%)
    1 (0.3%) 154 (1.8%)
    357 (99.7%) 8,539 (98.2%)
    142 2,752
    Nationally influenza B/Victoria viruses have been reported more frequently than other influenza viruses this season. However, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses. The predominant virus varies by region. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.

    The predominant virus also varies by age group. Nationally, influenza B viruses are the most commonly reported influenza viruses among children and young adults age 0-4 years (58% of reported viruses) and 5-24 years (72% of reported viruses), while A(H1N1)pdm09 viruses are the most commonly reported influenza viruses among persons 25-64 years (50% of reported viruses) and 65 years of age and older (57% of reported viruses). For this season, 53% of influenza positive specimens reported by public health laboratories were among persons less than 25 years of age and only 12% were from persons age 65 and older. INFLUENZA Virus Isolated
    View Chart Data | View Full Screen

    Additional virologic surveillance information for current and past seasons:
    Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
    Influenza Virus Characterization

    CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

    CDC genetically characterized 1,128 influenza viruses collected in the U.S. from September 29, 2019, to January 25, 2020.
    354
    6B.1A 354 (100%)
    276
    3C.2a 268 (97.1%) 2a1 268 (97.1%)
    2a2 0
    2a3 0
    2a4 0
    3C.3a 8 (2.9%) 3a 8 (2.9%)
    451
    V1A 451 (100%) V1A 0
    V1A.1 40 (8.9%)
    V1A.3 411 (91.1%)
    47
    Y3 47 (100%)
    CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 225 influenza viruses collected in the United States from September 29, 2019, to January 25, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

    Influenza A Viruses
    • A (H1N1)pdm09: 74 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and all were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines.
    • A (H3N2): 53 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 22 (41.5%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.



    Influenza B Viruses
    • B/Victoria: 88 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 53 (60.2%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
    • B/Yamagata: 10 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 10 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.




    CDC assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
    1,119 355 270 447 47
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    1 (0.1%) 1 (0.3%) (0.0%) (0.0%) (0.0%)
    1,119 355 270 447 47
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    1 (0.1%) 1 (0.3%) (0.0%) (0.0%) (0.0%)
    1,119 355 270 447 47
    1 (0.1%) (0.0%) (0.0%) 1 (0.2%) (0.0%)
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    1,115 352 270 446 47
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    Outpatient Illness Surveillance

    ILINet

    Nationwide during week 4, 5.7% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%. national levels of ILI and ARI
    View Chart Data (current season only) | View Full Screen

    On a regional level, the percentage of outpatient visits for ILI ranged from 4.1% to 7.7% during week 4. All regions reported a percentage of outpatient visits for ILI which is above their region-specific baselines. ILI Activity Map

    Data collected in ILINet are used to produce a measure of ILI activity* by state.

    During week 4, the following ILI activity levels were experienced:
    • High – the District of Columbia, New York City, Puerto Rico, and 41 states (Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Minnesota, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
    • Moderate – seven states (Alaska, Iowa, Michigan, Montana, Nevada, New Hampshire, and Ohio)
    • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands and two states (Delaware and Idaho).

    *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.


    Additional information about medically attended visits for ILI for current and past seasons:
    Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


    Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

    The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.

    During week 4 the following influenza activity was reported:
    • Widespread – Puerto Rico and 49 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
    • Regional – one state (Hawaii)
    • Local – the District of Columbia
    • Sporadic – the U.S. Virgin Islands
    • Guam did not report.

    Additional geographic spread surveillance information for current and past seasons:
    Surveillance Methods | FluView Interactive

    Influenza-Associated Hospitalizations

    The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.

    A total of 8,633 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and January 25, 2020; 5,173 (59.9%) were associated with influenza A virus, 3,401 (39.4%) with influenza B virus, 27 (0.3%) with influenza A virus and influenza B virus co-infection, and 32 (0.4%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,080 (91.1%) were A(H1N1)pdm09 virus and 106 (8.9%) were A(H3N2).

    The overall cumulative hospitalization rate was 29.7 per 100,000 population which is similar to what has been seen during recent previous influenza seasons at this time of year. Rates in children and young adults are higher than at this time in recent seasons.

    Click on graph to launch interactive tool View Full Screen

    The highest rate of hospitalization is among adults aged ≥65, followed by children aged 0-4 years and adults aged 50-64 years.
    Overall 29.7
    0-4 years 48.8
    5-17 years 13.4
    18-49 years 16.9
    50-64 years 36.7
    65+ years 71.3

    Among 1,108 hospitalized adults with information on underlying medical conditions, 91.5% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 271 hospitalized children with information on underlying medical conditions, 46.5% had at least one underlying medical condition; the most commonly reported was asthma. Among 216 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 26.4% were pregnant.

    Click on graph to launch interactive tool2 View Full Screen

    Additional hospitalization surveillance information for current and past seasons and additional age groups:
    Surveillance Methods | FluView Interactive


    Pneumonia and Influenza (P&I) Mortality Surveillance

    Based on National Center for Health Statistics (NCHS) mortality surveillance data available on January 30, 2020, 6.7% of the deaths occurring during the week ending January 18, 2020 (week 3) were due to P&I. This percentage is below the epidemic threshold of 7.2% for week 3. INFLUENZA Virus Isolated
    View Chart Data | View Full Screen

    Additional pneumonia and influenza mortality surveillance information for current and past seasons:
    Surveillance Methods | FluView Interactive


    Influenza-Associated Pediatric Mortality

    Fourteen influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 45 and 4 (the weeks ending November 9, 2019 and January 25, 2020) were reported to CDC during week 4. Eight were associated with influenza B viruses; one had a lineage determined and was a B/Victoria virus. Six were associated with influenza A viruses, and three were subtyped; all were A(H1N1)pdm09 viruses.

    Of the 68 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
    • 45 deaths were associated with influenza B viruses, and eight had a lineage determined; all were B/Victoria viruses.
    • 23 deaths were associated with influenza A viruses, and 13 were subtyped; all were A(H1N1)pdm09 viruses.
    Click on image to launch interactive tool
    View Full Screen

    Additional pediatric mortality surveillance information for current and past seasons:
    Surveillance Methods | FluView Interactive



    Additional National and International Influenza Surveillance Information

    FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

    National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html

    U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information



    World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.

    WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).

    Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.

    Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/

    Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports






    Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.


    An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.

    --------------------------------------------------------------------------------



    Page last reviewed: January 31, 2020, 11:00 AM
    Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)Seasonal Influenza (Flu)What CDC Does
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    • #17
      Weekly U.S. Influenza Surveillance Report


      Key Updates for Week 5, ending February 1, 2020

      Key indicators that track flu activity remain high and, after falling during the first two weeks of the year, increased over the last three weeks. Indicators that track overall severity (hospitalizations and deaths) are not high at this point in the season. Viruses

      Clinical Labs
      The percentage of respiratory specimens testing positive for influenza at clinical laboratories increased from 28.4% last week to 29.8% this week.

      Public Health Labs
      Numbers of influenza B/Victoria and A(H1N1)pdm09 viruses are approximately equal for the season overall, with continued increases in influenza A(H1N1)pdm09 viruses in recent weeks.

      Virus Characterization
      Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report. Illness

      Outpatient Illness: ILINet
      Visits to health care providers for influenza-like illness (ILI) increased from 6.0% last week to 6.7% this week. All regions remain above their baselines.

      Outpatient Illness: ILINet Activity Map
      Flu Activity & Surveillance

      The number of jurisdictions experiencing high ILI activity increased from 44 last week to 47 this week.

      Geographic Spread
      Flu Spread Map

      The number of jurisdictions reporting regional or widespread influenza activity remained at 51 this week. Severe Disease

      Hospitalizations
      The overall hospitalization rate for the season increased to 35.5 per 100,000. This is similar to what has been seen at this time during recent seasons.

      P&I Mortality
      The percentage of deaths attributed to pneumonia and influenza is 7.1%, below the epidemic threshold of 7.2%.

      Pediatric Deaths
      10 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 78.

      All data are preliminary and may change as more reports are received.

      A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

      Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

      Key Points
      • Outpatient ILI and laboratory data remain elevated and increased again this week. Nationally, and in some regions, the proportion of influenza A(H1N1)pdm09 viruses compared to influenza B viruses is increasing.
      • Overall, hospitalization rates remain similar to this time during recent seasons, but rates among children and young adults are higher at this time than in recent seasons.
      • Pneumonia and influenza mortality has been low, but 78 influenza-associated deaths in children have been reported so far this season.
      • CDC estimates that so far this season there have been at least 22 million flu illnesses, 210,000 hospitalizations and 12,000 deaths from flu.
      • Flu vaccine effectiveness estimates will be available later this month, but vaccination is always the best way to prevent flu and its potentially serious complications.
      • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.

      U.S. Virologic Surveillance

      Clinical Laboratories

      The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
      53,247 738,331
      15,875 (29.8%) 129,997 (17.6%)
      8,637 (54.4%) 52,928 (40.7%)
      7,238 (45.6%) 77,069 (59.3%)

      The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among children and young adults age 0-4 years (56% of reported viruses) and 5-24 years (73% of reported viruses), while A(H1N1)pdm09 viruses are the most commonly reported influenza viruses among persons 25-64 years (53% of reported viruses) and 65 years of age and older (60% of reported viruses). For this season, 52% of influenza positive specimens reported by public health laboratories were among persons less than 25 years of age and less than 13% were from persons age 65 and older. INFLUENZA Virus Isolated
      View Chart Data | View Full Screen Public Health Laboratories

      The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
      2,129 46,258
      1,365 24,403
      898 (65.8%) 11,670 (47.8%)
      810 (95.7%) 10,087 (88.9%)
      36 (4.3%) 1,255 (11.1%)
      52 328
      467 (34.2%) 12,733 (52.2%)
      2 (0.5%) 168 (1.7%)
      393 (99.5%) 9,765 (98.3%)
      72 2,800
      Nationally, influenza B/Victoria viruses have been reported more frequently than other influenza viruses this season. However, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses. The predominant virus varies by region. Regional and state level data about circulating influenza viruses can be found on FluView Interactive. INFLUENZA Virus Isolated
      View Chart Data | View Full Screen

      Additional virologic surveillance information for current and past seasons:
      Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
      Influenza Virus Characterization

      CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

      CDC genetically characterized 1,260 influenza viruses collected in the U.S. from September 29, 2019, to February 1, 2020.
      397
      6B.1A 397 (100%)
      301
      3C.2a 290 (96.3%) 2a1 290 (96.3%)
      2a2 0
      2a3 0
      2a4 0
      3C.3a 11 (3.7%) 3a 11 (3.7%)
      509
      V1A 509 (100%) V1A 0
      V1A.1 42 (8.3%)
      V1A.3 467 (91.7%)
      53
      Y3 53 (100%)
      CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 241 influenza viruses collected in the United States from September 29, 2019, to February 1, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

      Influenza A Viruses
      • A (H1N1)pdm09: 74 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and all 74 (100%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines.
      • A (H3N2): 69 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 30 (43.5%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.



      Influenza B Viruses
      • B/Victoria: 88 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 53 (60.2%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
      • B/Yamagata: 10 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 10 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.




      CDC assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
      1,192 374 287 481 50
      (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
      1 (0.1%) 1 (0.3%) (0.0%) (0.0%) (0.0%)
      1,192 374 287 481 50
      (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
      1 (0.1%) 1 (0.3%) (0.0%) (0.0%) (0.0%)
      1,192 374 287 481 50
      1 (0.1%) (0.0%) (0.0%) 1 (0.2%) (0.0%)
      (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
      1,246 395 294 504 53
      (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)

      A total of 259 additional viruses (118 H1pdm09, 19 H3, and 122 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Michigan, Nevada, New York, North Carolina, Pennsylvania, Virginia, and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Two (1.7%) of the 118 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase that confers resistance to oseltamivir and potential resistance to peramivir. No markers of resistance to neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.

      Outpatient Illness Surveillance

      ILINet

      Nationwide during week 5, 6.7% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%. national levels of ILI and ARI
      View Chart Data (current season only) | View Full Screen

      On a regional level, the percentage of outpatient visits for ILI ranged from 4.0% to 10.9% during week 5. All regions reported a percentage of outpatient visits for ILI above their region-specific baselines. ILI Activity Map

      Data collected in ILINet are used to produce a measure of ILI activity* by state.

      During week 5, the following ILI activity levels were experienced:
      • High – New York City, Puerto Rico, and 45 states (Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
      • Moderate – the District of Columbia, the U.S. Virgin Islands, and two states (Nevada and New Hampshire)
      • Low - two states (Alaska and Delaware)
      • Minimal - one state (Idaho)

      *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.


      Additional information about medically attended visits for ILI for current and past seasons:
      Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


      Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

      The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.

      During week 5, the following influenza activity was reported:
      • Widespread – Puerto Rico and 48 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
      • Regional – two states (Hawaii and Oregon)
      • Local – the District of Columbia
      • Sporadic – the U.S. Virgin Islands
      • Guam did not report.

      Additional geographic spread surveillance information for current and past seasons:
      Surveillance Methods | FluView Interactive

      Influenza-Associated Hospitalizations

      The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.

      A total of 10,314 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and February 1, 2020; 6,416 (62.2%) were associated with influenza A virus, 3,835 (37.2%) with influenza B virus, 31 (0.3%) with influenza A virus and influenza B virus co-infection, and 32 (0.3%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,397 (92.6%) were A(H1N1)pdm09 virus and 112 (7.4%) were A(H3N2).

      The overall cumulative hospitalization rate was 35.5 per 100,000 population which is similar to what has been seen during recent previous influenza seasons at this time of year. Rates in children and young adults are higher than at this time in recent seasons.

      Click on graph to launch interactive tool View Full Screen

      The highest rate of hospitalization is among adults aged ≥65, followed by children aged 0-4 years and adults aged 50-64 years.
      Overall 35.5
      0-4 years 56.9
      5-17 years 15.1
      18-49 years 20.2
      50-64 years 44.9
      65+ years 85.1

      Among 1,332 hospitalized adults with information on underlying medical conditions, 91.6% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 297 hospitalized children with information on underlying medical conditions, 46.5% had at least one underlying medical condition; the most commonly reported was asthma. Among 253 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 25.3% were pregnant.

      Click on graph to launch interactive tool2 View Full Screen

      Additional hospitalization surveillance information for current and past seasons and additional age groups:
      Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


      Pneumonia and Influenza (P&I) Mortality Surveillance

      Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 6, 2020, 7.1% of the deaths occurring during the week ending January 25, 2020 (week 4) were due to P&I. This percentage is below the epidemic threshold of 7.2% for week 4. INFLUENZA Virus Isolated
      View Chart Data | View Full Screen

      Additional pneumonia and influenza mortality surveillance information for current and past seasons:
      Surveillance Methods | FluView Interactive


      Influenza-Associated Pediatric Mortality

      Ten influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 1 and 4 (the weeks ending January 4, 2020 and January 25, 2020) were reported to CDC during week 5. Seven were associated with influenza B viruses; none had a lineage determined. Three were associated with influenza A viruses, and one was subtyped and was an A(H1N1)pdm09 virus.

      One influenza-associated pediatric death occurring during the 2018-2019 season in week 30 (the week ending July 27, 2019) was reported to CDC during week 5, bringing the total during that season to 144. This was associated with an influenza A virus.

      Of the 78 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
      • 52 deaths were associated with influenza B viruses, and nine had a lineage determined; all were B/Victoria viruses.
      • 26 deaths were associated with influenza A viruses, and 16 were subtyped; all were A(H1N1)pdm09 viruses.
      Click on image to launch interactive tool
      View Full Screen

      Additional pediatric mortality surveillance information for current and past seasons:
      Surveillance Methods | FluView Interactive



      Additional National and International Influenza Surveillance Information

      FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

      National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html

      U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information



      World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.

      WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).

      Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.

      Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/

      Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports






      Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.


      An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.

      --------------------------------------------------------------------------------



      Page last reviewed: February 7, 2020, 11:00 AM
      Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)Seasonal Influenza (Flu)What CDC Does
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      H1N1 Flu Pandemic 2009-2019: A Decade Later
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      • #18
        Weekly U.S. Influenza Surveillance Report


        Key Updates for Week 6, ending February 8, 2020

        Key indicators that track flu activity remain high and, after falling during the first two weeks of the year, increased over the last four weeks. Indicators that track overall severity (hospitalizations and deaths) are not high at this point in the season. Viruses

        Clinical Labs
        The percentage of respiratory specimens testing positive for influenza at clinical laboratories increased from 30.1% last week to 30.8% this week.

        Public Health Labs
        Numbers of influenza B/Victoria and A(H1N1)pdm09 viruses are approximately equal for the season overall, with continued increases in influenza A(H1N1)pdm09 viruses in recent weeks.

        Virus Characterization
        Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report. Illness

        Outpatient Illness: ILINet
        Visits to health care providers for influenza-like illness (ILI) increased from 6.6% last week to 6.8% this week. All regions remain above their baselines.

        Outpatient Illness: ILINet Activity Map
        Flu Activity & Surveillance

        The number of jurisdictions experiencing high ILI activity decreased slightly from 47 last week to 46 this week.

        Geographic Spread
        spread map week 6

        The number of jurisdictions reporting regional or widespread influenza activity remained at 51 this week. Severe Disease

        Hospitalizations
        The overall hospitalization rate for the season increased to 41.9 per 100,000. This is similar to what has been seen at this time during recent seasons.

        P&I Mortality
        The percentage of deaths attributed to pneumonia and influenza is 6.8%, below the epidemic threshold of 7.3%.

        Pediatric Deaths
        14 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 92.

        All data are preliminary and may change as more reports are received.

        A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

        Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

        Key Points
        • Outpatient ILI and clinical laboratory data remain elevated and increased again this week. Nationally, and in some regions, the proportion of influenza A(H1N1)pdm09 viruses compared to influenza B viruses is increasing.
        • Overall, hospitalization rates remain similar to this time during recent seasons, but rates among children and young adults are higher at this time than in recent seasons.
        • Pneumonia and influenza mortality has been low, but 92 influenza-associated deaths in children have been reported so far this season.
        • CDC estimates that so far this season there have been at least 26 million flu illnesses, 250,000 hospitalizations and 14,000 deaths from flu.
        • Flu vaccine effectiveness estimates will be available next week. Vaccination is always the best way to prevent flu and its potentially serious complications.
        • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.

        U.S. Virologic Surveillance

        Clinical Laboratories

        The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
        54,982 823,555
        16,934 (30.8%) 155,014 (18.8%)
        10,067 (59.4%) 67,285 (43.4%)
        6,867 (40.6%) 87,729 (56.6%)

        The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among children and young adults age 0-4 years (56% of reported viruses) and 5-24 years (70% of reported viruses), while A(H1N1)pdm09 viruses are the most commonly reported influenza viruses among persons 25-64 years (55% of reported viruses) and 65 years of age and older (62% of reported viruses). For this season, 51% of influenza positive specimens reported by public health laboratories were among persons less than 25 years of age and less than 13% were from persons age 65 and older. INFLUENZA Virus Isolated
        View Chart Data | View Full Screen Public Health Laboratories

        The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
        1,936 51,930
        1,258 28,040
        833 (66.2%) 13,822 (49.3%)
        721 (95.5%) 12,088 (90.0%)
        34 (4.5%) 1,349 (10.0%)
        78 385
        425 (33.8%) 14,218 (50.7%)
        1 (0.3%) 178 (1.6%)
        361 (99.7%) 11,080 (98.4%)
        63 2,960
        Nationally, influenza B/Victoria viruses have been reported more frequently than other influenza viruses this season. However, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses. The predominant virus varies by region. Regional and state level data about circulating influenza viruses can be found on FluView Interactive. INFLUENZA Virus Isolated
        View Chart Data | View Full Screen

        Additional virologic surveillance information for current and past seasons:
        Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
        Influenza Virus Characterization

        CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

        CDC genetically characterized 1,462 influenza viruses collected in the U.S. from September 29, 2019, to February 8, 2020.
        484
        6B.1A 484 (100%)
        339
        3C.2a 325 (95.9%) 2a1 325 (95.9%)
        2a2 0
        2a3 0
        2a4 0
        3C.3a 14 (4.1%) 3a 14 (4.1%)
        579
        V1A 579 (100%) V1A 0
        V1A.1 49 (8.5%)
        V1A.3 530 (91.5%)
        60
        Y3 60 (100%)
        CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 244 influenza viruses collected in the United States from September 29, 2019, to February 8, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

        Influenza A Viruses
        • A (H1N1)pdm09: 74 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and all 74 (100%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines.
        • A (H3N2): 72 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 31 (43.1%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.



        Influenza B Viruses
        • B/Victoria: 88 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 53 (60.2%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
        • B/Yamagata: 10 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 10 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.




        CDC assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
        1,415 469 326 560 60
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        1 (0.1%) 1 (0.2%) (0.0%) (0.0%) (0.0%)
        1,415 469 326 560 60
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        1 (0.1%) 1 (0.2%) (0.0%) (0.0%) (0.0%)
        1,415 469 326 560 60
        1 (0.1%) (0.0%) (0.0%) 1 (0.2%) (0.0%)
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        1,409 464 327 558 60
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)

        A total of 353 additional viruses (173 H1pdm09, 22 H3, and 158 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Two (1.2%) of the 173 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase that confers resistance to oseltamivir and potential resistance to peramivir. No markers of resistance to neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.

        Outpatient Illness Surveillance

        ILINet

        Nationwide during week 6, 6.8% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%. national levels of ILI and ARI
        View Chart Data (current season only) | View Full Screen

        On a regional level, the percentage of outpatient visits for ILI ranged from 3.6% to 10.8% during week 6. All regions reported a percentage of outpatient visits for ILI above their region-specific baselines. ILI Activity Map

        Data collected in ILINet are used to produce a measure of ILI activity* by state.

        During week 6, the following ILI activity levels were experienced:
        • High – New York City, Puerto Rico, and 44 states (Alabama, Arizona, Arkansas, California, Colorado, Connecticut, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
        • Moderate – two states (Nevada and Oregon)
        • Low - the District of Columbia and two states (Alaska and Florida)
        • Minimal - one state (Idaho)
        • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands and one state (Delaware)

        *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.


        Additional information about medically attended visits for ILI for current and past seasons:
        Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


        Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

        The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.

        During week 6, the following influenza activity was reported:
        • Widespread – Puerto Rico and 48 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
        • Regional – two states (Hawaii and Oregon)
        • Local – the District of Columbia
        • Sporadic – the U.S. Virgin Islands
        • Guam did not report.

        Additional geographic spread surveillance information for current and past seasons:
        Surveillance Methods | FluView Interactive

        Influenza-Associated Hospitalizations

        The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.

        A total of 12,167 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and February 8, 2020; 7,881 (64.8%) were associated with influenza A virus, 4,213 (34.6%) with influenza B virus, 39 (0.3%) with influenza A virus and influenza B virus co-infection, and 34 (0.3%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,782 (93.2%) were A(H1N1)pdm09 virus and 129 (6.8%) were A(H3N2).

        The overall cumulative hospitalization rate was 41.9 per 100,000 population which is similar to what has been seen during recent previous influenza seasons at this time of year. Rates in children and young adults are higher than at this time in recent seasons.

        Click on graph to launch interactive tool View Full Screen

        The highest rate of hospitalization is among adults aged ≥65, followed by children aged 0-4 years and adults aged 50-64 years.
        Overall 41.9
        0-4 years 65.9
        5-17 years 17.3
        18-49 years 23.5
        50-64 years 53.9
        65+ years 101.6

        Among 1,573 hospitalized adults with information on underlying medical conditions, 91.9% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 333 hospitalized children with information on underlying medical conditions, 46.2% had at least one underlying medical condition; the most commonly reported was asthma. Among 299 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 26.4% were pregnant.

        Click on graph to launch interactive tool2 View Full Screen

        Additional hospitalization surveillance information for current and past seasons and additional age groups:
        Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


        Pneumonia and Influenza (P&I) Mortality Surveillance

        Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 13, 2020, 6.8% of the deaths occurring during the week ending February 1, 2020 (week 5) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 5. INFLUENZA Virus Isolated
        View Chart Data | View Full Screen

        Additional pneumonia and influenza mortality surveillance information for current and past seasons:
        Surveillance Methods | FluView Interactive


        Influenza-Associated Pediatric Mortality

        14 influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 52 and 6 (the weeks ending December 28, 2019 and February 8, 2020) were reported to CDC during week 6. 10 were associated with influenza B viruses; one had a lineage determined and was a B/Victoria virus. Four were associated with influenza A viruses, and two were subtyped; one was an A(H1N1)pdm09 virus and one was an A(H3) virus.

        Of the 92 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
        • 62 deaths were associated with influenza B viruses, and 10 had a lineage determined; all were B/Victoria viruses.
        • 30 deaths were associated with influenza A viruses, and 18 were subtyped; 17 were A(H1N1)pdm09 viruses and one was an A(H3) virus.
        Click on image to launch interactive tool
        View Full Screen

        Additional pediatric mortality surveillance information for current and past seasons:
        Surveillance Methods | FluView Interactive



        Additional National and International Influenza Surveillance Information

        FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

        National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html

        U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information



        World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.

        WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).

        Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.

        Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/

        Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports






        Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.


        An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.

        --------------------------------------------------------------------------------



        Page last reviewed: February 14, 2020, 11:00 AM
        Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)Seasonal Influenza (Flu)What CDC Does
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        To receive weekly email updates about Seasonal Flu, enter your email address: Email Address
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        Comment


        • #19
          Weekly U.S. Influenza Surveillance Report


          Key Updates for Week 7, ending February 15, 2020

          Key indicators that track flu activity remain high but decreased slightly this week. Indicators that track overall severity (hospitalizations and deaths) are not high at this point in the season. Viruses

          Clinical Labs
          The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 30.3% last week to 29.6% this week.

          Public Health Labs
          Numbers of influenza B/Victoria and A(H1N1)pdm09 viruses are approximately equal for the season overall, with continued increases in influenza A(H1N1)pdm09 viruses in recent weeks.

          Virus Characterization
          Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report. Illness

          Outpatient Illness: ILINet
          Visits to health care providers for influenza-like illness (ILI) decreased from 6.7% last week to 6.1% this week. All regions remain above their baselines.

          Outpatient Illness: ILINet Activity Map
          Flu Activity & Surveillance

          The number of jurisdictions experiencing high ILI activity remained at 46 this week.

          Geographic Spread
          Spread Map

          The number of jurisdictions reporting regional or widespread influenza activity remained at 51 this week. Severe Disease

          Hospitalizations
          The overall hospitalization rate for the season increased to 47.4 per 100,000. This is similar to what has been seen at this time during recent seasons.

          P&I Mortality
          The percentage of deaths attributed to pneumonia and influenza is 6.8%, below the epidemic threshold of 7.3%.

          Pediatric Deaths
          13 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 105.

          All data are preliminary and may change as more reports are received.

          A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

          Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.
          • Outpatient ILI and clinical laboratory data remain elevated but decreased slightly this week. The overall decrease in the percentage of specimens testing positive for influenza was due to a decrease in the percentage of specimens testing positive for influenza B. The percentage of specimens testing positive for influenza A continued to increase.
          • Overall, hospitalization rates remain similar to this time during recent seasons, but rates among children and young adults are higher at this time than in recent seasons.
          • Pneumonia and influenza mortality has been low, but 105 influenza-associated deaths in children have been reported so far this season.
          • CDC estimates that so far this season there have been at least 29 million flu illnesses, 280,000 hospitalizations and 16,000 deaths from flu.
          • Interim estimates of 2019-2020 flu vaccine effectiveness were released this week. So far this season, flu vaccines are reducing doctor’s visits for flu illness by 45% overall and 55% in children.
          • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.

          U.S. Virologic Surveillance

          Clinical Laboratories

          The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
          49,510 888,399
          14,657 (29.6%) 174,037 (19.6%)
          9,305 (63.5%) 79,269 (45.5%)
          5,352 (36.5%) 94,768 (54.5%)
          INFLUENZA Virus Isolated
          View Chart Data | View Full Screen Public Health Laboratories

          The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
          1,626 57,630
          981 31,638
          637 (64.9%) 16,160 (51.1%)
          531 (96.0%) 14,320 (90.9%)
          22 (4.0%) 1,427 (9.1%)
          84 413
          344 (35.1%) 15,478 (48.9%)
          3 (1.6%) 191 (1.6%)
          180 (98.4%) 11,796 (98.4%)
          161 3,491
          While influenza B/Victoria viruses predominated earlier in the season, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses. For the season, the number of B/Victoria and A(H1N1)pdm09 viruses are approximately equal. The predominant virus varies by region. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.

          The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among children and young adults age 0-4 years (53% of reported viruses) and 5-24 years (68% of reported viruses), while A(H1N1)pdm09 viruses are the most commonly reported influenza viruses among persons 25-64 years (57% of reported viruses) and 65 years of age and older (64% of reported viruses). For this season, 51% of influenza positive specimens reported by public health laboratories were among persons less than 25 years of age and less than 13% were from persons age 65 and older. INFLUENZA Virus Isolated
          View Chart Data | View Full Screen

          Additional virologic surveillance information for current and past seasons:
          Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
          Influenza Virus Characterization

          CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza viruses. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people. Interim estimates of 2019-2020 flu vaccine effectiveness were released this week.

          CDC genetically characterized 1,667 influenza viruses collected in the U.S. from September 29, 2019, to February 15, 2020.
          563
          6B.1A 563 (100%)
          381
          3C.2a 365 (95.8%) 2a1 365 (95.8%)
          2a2 0
          2a3 0
          2a4 0
          3C.3a 16 (4.2%) 3a 16 (4.2%)
          655
          V1A 655 (100%) V1A 0
          V1A.1 50 (7.6%)
          V1A.3 605 (92.4%)
          68
          Y3 68 (100%)
          CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 244 influenza viruses collected in the United States from September 29, 2019, to February 15, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

          Influenza A Viruses
          • A (H1N1)pdm09: 74 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and all 74 (100%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines.
          • A (H3N2): 72 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 31 (43.1%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.



          Influenza B Viruses
          • B/Victoria: 88 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 53 (60.2%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
          • B/Yamagata: 10 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 10 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.




          CDC assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
          1,613 547 367 632 67
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          1 (0.1%) 1 (0.2%) (0.0%) (0.0%) (0.0%)
          1,613 547 367 632 67
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          1 (0.1%) 1 (0.2%) (0.0%) (0.0%) (0.0%)
          1,613 547 367 632 67
          1 (0.1%) (0.0%) (0.0%) 1 (0.2%) (0.0%)
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          1,767 567 453 676 71
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)

          A total of 353 additional viruses (173 A(H1N1)pdm09, 22 A(H3N2), and 158 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Two (1.2%) of the 173 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase that confers resistance to oseltamivir and potential resistance to peramivir. No markers of resistance to neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.

          Outpatient Illness Surveillance

          ILINet

          Nationwide during week 7, 6.1% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%. national levels of ILI and ARI
          View Chart Data (current season only) | View Full Screen

          On a regional level, the percentage of outpatient visits for ILI ranged from 3.4% to 9.7% during week 7. All regions reported a percentage of outpatient visits for ILI above their region-specific baselines. ILI Activity Map

          Data collected in ILINet are used to produce a measure of ILI activity* by state.

          During week 7, the following ILI activity levels were experienced:
          • High – New York City, Puerto Rico, and 44 states (Alabama, Arkansas, California, Colorado, Connecticut, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
          • Moderate – the District of Columbia and four states (Arizona, Delaware, Florida, and Nevada)
          • Low - the U.S. Virgin Islands
          • Minimal - two states (Alaska and Idaho)

          *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.


          Additional information about medically attended visits for ILI for current and past seasons:
          Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


          Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

          The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.

          During week 7, the following influenza activity was reported:
          • Widespread – Puerto Rico and 47 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
          • Regional – three states (Hawaii, Idaho and Oregon)
          • Local – the District of Columbia
          • Sporadic – the U.S. Virgin Islands
          • Guam did not report.

          Additional geographic spread surveillance information for current and past seasons:
          Surveillance Methods | FluView Interactive

          Influenza-Associated Hospitalizations

          The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.

          A total of 13,775 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and February 15, 2020; 9,168 (66.6%) were associated with influenza A virus, 4,529 (32.9%) with influenza B virus, 42 (0.3%) with influenza A virus and influenza B virus co-infection, and 36 (0.3%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 2,385 (93.3%) were A(H1N1)pdm09 virus and 172 (6.7%) were A(H3N2).

          The overall cumulative hospitalization rate was 47.4 per 100,000 population which is similar to what has been seen during recent previous influenza seasons at this time of year. Rates in children and young adults are higher than at this time in recent seasons.

          Click on graph to launch interactive tool View Full Screen

          The highest rate of hospitalization is among adults aged ≥65, followed by children aged 0-4 years and adults aged 50-64 years.
          Overall 47.4
          0-4 years 72.5
          5-17 years 19.2
          18-49 years 26.3
          50-64 years 61.5
          65+ years 116.7

          Among 1,833 hospitalized adults with information on underlying medical conditions, 92.5% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 360 hospitalized children with information on underlying medical conditions, 47.2% had at least one underlying medical condition; the most commonly reported was asthma. Among 342 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 26% were pregnant.

          Click on graph to launch interactive tool2 View Full Screen

          Additional hospitalization surveillance information for current and past seasons and additional age groups:
          Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


          Pneumonia and Influenza (P&I) Mortality Surveillance

          Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 20, 2020, 6.8% of the deaths occurring during the week ending February 8, 2020 (week 6) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 6. INFLUENZA Virus Isolated
          View Chart Data | View Full Screen

          Additional pneumonia and influenza mortality surveillance information for current and past seasons:
          Surveillance Methods | FluView Interactive


          Influenza-Associated Pediatric Mortality

          13 influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 2 and 7 (the weeks ending January 11, 2020 and February 15, 2020) were reported to CDC during week 7. 10 were associated with influenza B viruses, and two had a lineage determined; both B/Victoria viruses. Three were associated with influenza A viruses, and two were subtyped; both A(H1N1)pdm09 viruses.

          Of the 105 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
          • 72 deaths were associated with influenza B viruses, and 12 had a lineage determined; all were B/Victoria viruses.
          • 33 deaths were associated with influenza A viruses, and 20 were subtyped; 19 were A(H1N1)pdm09 viruses and one was an A(H3) virus.
          Click on image to launch interactive tool
          View Full Screen

          Additional pediatric mortality surveillance information for current and past seasons:
          Surveillance Methods | FluView Interactive



          Additional National and International Influenza Surveillance Information

          FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

          National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html

          U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information



          World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.

          WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).

          Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.

          Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/

          Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports






          Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.


          An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.

          --------------------------------------------------------------------------------



          Page last reviewed: February 21, 2020, 11:00 AM
          Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)Seasonal Influenza (Flu)What CDC Does
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          Comment


          • #20
            Weekly U.S. Influenza Surveillance Report


            Key Updates for Week 8, ending February 22, 2020

            Key indicators that track flu activity remain high but decreased for the second week in a row. Severity indicators (hospitalizations and deaths) remain moderate to low overall, but hospitalization rates differ by age group, with high rates among children and young adults. Viruses

            Clinical Labs
            The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 29.7% last week to 26.4% this week.

            Public Health Labs
            Numbers of influenza B/Victoria and A(H1N1)pdm09 viruses are approximately equal for the season overall, with continued increases in influenza A(H1N1)pdm09 viruses in recent weeks.

            Virus Characterization
            Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report. Illness

            Outpatient Illness: ILINet
            Visits to health care providers for influenza-like illness (ILI) decreased from 6.1% last week to 5.5% this week. All regions remain above their baselines.

            Outpatient Illness: ILINet Activity Map
            Flu Activity & Surveillance

            The number of jurisdictions experiencing high ILI activity decreased slightly from 46 last week to 45 this week.

            Geographic Spread
            Spread map

            The number of jurisdictions reporting regional or widespread influenza activity decreased from 51 last week to 50 this week. Severe Disease

            Hospitalizations
            The overall cumulative hospitalization rate for the season increased to 52.7 per 100,000.

            P&I Mortality
            The percentage of deaths attributed to pneumonia and influenza is 6.9%, below the epidemic threshold of 7.3%.

            Pediatric Deaths
            20 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 125.

            All data are preliminary and may change as more reports are received.

            A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

            Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

            Key Points:
            • Outpatient ILI and clinical laboratory data remain elevated but decreased for the second week in a row. The percentage of specimens testing positive for both influenza A and influenza B viruses decreased.
            • Overall, hospitalization rates remain similar to this time during recent seasons, but rates among school aged children and young adults are higher at this time than in recent seasons and rates among children 0-4 years old are now the highest CDC has on record at this point in the season, surpassing rates reported during the second wave of the 2009 H1N1 pandemic.
            • Pneumonia and influenza mortality has been low, but 125 influenza-associated deaths in children have been reported so far this season. This number is higher for the same time period than in every season since reporting began in 2004-05, except for the 2009 pandemic.
            • CDC estimates that so far this season there have been at least 32 million flu illnesses, 310,000 hospitalizations and 18,000 deaths from flu.
            • Interim estimates of 2019-2020 flu vaccine effectiveness were released last week. So far this season, flu vaccines are reducing doctor’s visits for flu illness by 45% overall and 55% in children.
            • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.

            U.S. Virologic Surveillance

            Clinical Laboratories

            The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
            42,587 948,064
            11,249 (26.4%) 190,362 (20.1%)
            7,633 (67.9%) 90,382 (47.5%)
            3,616 (32.1%) 99,980 (52.5%)
            INFLUENZA Virus Isolated
            View Chart Data | View Full Screen Public Health Laboratories

            The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
            1,783 62,234
            1,153 34,807
            835 (72.4%) 18,421 (52.9%)
            697 (94.8%) 16,409 (91.6%)
            38 (5.2%) 1,511 (8.4%)
            100 501
            318 (27.6%) 16,386 (47.1%)
            2 (0.7%) 205 (1.6%)
            277 (99.3%) 12,657 (98.4%)
            39 3,524
            While influenza B/Victoria viruses predominated earlier in the season, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses. For the season, the number of B/Victoria and A(H1N1)pdm09 viruses are approximately equal. The predominant virus varies by region. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.

            The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among children and young adults less than 25 years, while A viruses are the most commonly reported influenza viruses among persons 25 years and older. In the most recent weeks, influenza A viruses are the most commonly reported influenza viruses in all but the school aged children and young adults (5-24 years old). INFLUENZA Virus Isolated
            View Chart Data | View Full Screen

            Additional virologic surveillance information for current and past seasons:
            Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
            Influenza Virus Characterization

            CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza viruses. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people. Interim estimates of 2019-2020 flu vaccine effectiveness have been released.

            CDC genetically characterized 1,787 influenza viruses collected in the U.S. from September 29, 2019, to February 22, 2020.
            606
            6B.1A 606 (100%)
            406
            3C.2a 386 (95.1%) 2a1 386 (95.1%)
            2a2 0
            2a3 0
            2a4 0
            3C.3a 20 (4.9%) 3a 20 (4.9%)
            699
            V1A 699 (100%) V1A 0
            V1A.1 51 (7.3%)
            V1A.3 648 (92.7%)
            76
            Y3 76 (100%)
            CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 287 influenza viruses collected in the United States from September 29, 2019, to February 22, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

            Influenza A Viruses
            • A (H1N1)pdm09: 74 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and all 74 (100%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines.
            • A (H3N2): 72 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 31 (43.1%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.



            Influenza B Viruses
            • B/Victoria: 131 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 83 (63.4%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
            • B/Yamagata: 10 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 10 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.




            CDC assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
            1,776 606 399 695 76
            1 (0.1%) (0.0%) (0.0%) 1 (0.1%) (0.0%)
            3 (0.2%) 3 (0.5%) (0.0%) (0.0%) (0.0%)
            1,776 606 399 695 76
            (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
            4 (0.2%) 3 (0.5%) (0.0%) 1 (0.1%) (0.0%)
            1,776 606 399 695 76
            2 (0.1%) (0.0%) (0.0%) 2 (0.3%) (0.0%)
            (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
            1,926 626 484 737 79
            (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)

            A total of 416 additional viruses (199 A(H1N1)pdm09, 30 A(H3N2), and 187 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Two (1.0%) of the 199 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase that confers resistance to oseltamivir and potential resistance to peramivir. No markers of resistance to neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.

            Outpatient Illness Surveillance

            ILINet

            Nationwide during week 8, 5.5% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%. national levels of ILI and ARI
            View Chart Data (current season only) | View Full Screen

            On a regional level, the percentage of outpatient visits for ILI ranged from 3.6% to 8.8% during week 8. All regions reported a percentage of outpatient visits for ILI above their region-specific baselines. ILI Activity Map

            Data collected in ILINet are used to produce a measure of ILI activity* by state.

            During week 8, the following ILI activity levels were experienced:
            • High – New York City, Puerto Rico, and 43 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
            • Moderate – five states (Delaware, Nevada, North Dakota, Ohio, and Oregon)
            • Low - the District of Columbia and one state (Idaho)
            • Minimal - the U.S. Virgin Islands and one state (Florida)

            *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.


            Additional information about medically attended visits for ILI for current and past seasons:
            Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


            Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

            The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.

            During week 8, the following influenza activity was reported:
            • Widespread – Puerto Rico and 48 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
            • Regional – one state (Oregon)
            • Local – the District of Columbia and one state (Hawaii)
            • Sporadic – the U.S. Virgin Islands
            • Guam did not report.

            Additional geographic spread surveillance information for current and past seasons:
            Surveillance Methods | FluView Interactive

            Influenza-Associated Hospitalizations

            The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.

            A total of 15,319 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and February 22, 2020; 10,439 (68.1%) were associated with influenza A virus, 4,797 (31.3%) with influenza B virus, 47 (0.3%) with influenza A virus and influenza B virus co-infection, and 36 (0.2%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 2,834 (94.1%) were A(H1N1)pdm09 virus and 179 (5.9%) were A(H3N2).

            The overall cumulative hospitalization rate was 52.7 per 100,000 population which is similar to what has been seen during recent previous influenza seasons at this time of year. Rates in school aged children and young adults are higher than at this time in recent seasons, and rates among children 0-4 years old are now the highest CDC has on record at this point in the season, surpassing rates reported during the second wave of the 2009 H1N1 pandemic.

            Click on graph to launch interactive tool View Full Screen

            The highest rate of hospitalization is among adults aged ≥ 65, followed by children aged 0-4 years and adults aged 50-64 years.
            Overall 52.7
            0-4 years 80.1
            5-17 years 20.6
            18-49 years 28.6
            50-64 years 69.1
            65+ years 132.0

            Among 2,172 hospitalized adults with information on underlying medical conditions, 92.1% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 397 hospitalized children with information on underlying medical conditions, 48.6% had at least one underlying medical condition; the most commonly reported was asthma. Among 381 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 24.1% were pregnant.

            Click on graph to launch interactive tool2 View Full Screen

            Additional hospitalization surveillance information for current and past seasons and additional age groups:
            Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


            Pneumonia and Influenza (P&I) Mortality Surveillance

            Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 27, 2020, 6.9% of the deaths occurring during the week ending February 15, 2020 (week 7) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 7. INFLUENZA Virus Isolated
            View Chart Data | View Full Screen

            Additional pneumonia and influenza mortality surveillance information for current and past seasons:
            Surveillance Methods | FluView Interactive


            Influenza-Associated Pediatric Mortality

            20 influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 52 and 8 (the weeks ending December 28, 2019 and February 22, 2020) were reported to CDC during week 8. 15 were associated with influenza B viruses, and four had a lineage determined; all B/Victoria viruses. Five were associated with influenza A viruses, and three were subtyped; all A(H1N1)pdm09 viruses.

            Of the 125 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
            • 87 deaths were associated with influenza B viruses, and 18 had a lineage determined; all were B/Victoria viruses.
            • 38 deaths were associated with influenza A viruses, and 23 were subtyped; 22 were A(H1N1)pdm09 viruses and one was an A(H3) virus.

            Click on image to launch interactive tool
            View Full Screen

            Additional pediatric mortality surveillance information for current and past seasons:
            Surveillance Methods | FluView Interactive



            Additional National and International Influenza Surveillance Information

            FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

            National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html

            U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information



            World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.

            WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).

            Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.

            Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/

            Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports






            Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.


            An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.

            --------------------------------------------------------------------------------



            Page last reviewed: February 28, 2020, 11:00 AM
            Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)
            ...
            Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.
            Twitter: @RonanKelly13
            The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

            Comment


            • #21
              Weekly U.S. Influenza Surveillance Report


              Key Updates for Week 9, ending February 29, 2020

              Key indicators that track flu activity remain high but decreased for the third week in a row. Severity indicators (hospitalizations and deaths) remain moderate to low overall, but hospitalization rates differ by age group, with high rates among children and young adults. Viruses

              Clinical Labs
              The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 28.0% last week to 24.3% this week.

              Public Health Labs
              Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.

              Virus Characterization
              Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report. Illness

              Outpatient Illness: ILINet
              Visits to health care providers for influenza-like illness (ILI) decreased from 5.5% last week to 5.3% this week. All regions remain above their baselines.

              Outpatient Illness: ILINet Activity Map
              Flu Activity & Surveillance

              The number of jurisdictions experiencing high ILI activity decreased from 45 last week to 42 this week.

              Geographic Spread
              Spread Map week 9

              The number of jurisdictions reporting regional or widespread influenza activity increased from 50 last week to 51 this week. Severe Disease

              Hospitalizations
              The overall cumulative hospitalization rate for the season increased to 57.9 per 100,000.

              P&I Mortality
              The percentage of deaths attributed to pneumonia and influenza is 6.9%, below the epidemic threshold of 7.3%.

              Pediatric Deaths
              11 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 136.

              All data are preliminary and may change as more reports are received.

              A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

              Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

              Key Points:
              • Outpatient ILI and clinical laboratory data remain elevated but decreased for the third week in a row.
              • Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season. Previously, influenza B/Victoria viruses predominated nationally.
              • Overall, hospitalization rates remain similar to this time during recent seasons, but rates among school aged children and young adults are higher at this time than in recent seasons and rates among children 0-4 years old are now the highest CDC has on record at this point in the season, surpassing rates reported during the second wave of the 2009 H1N1 pandemic.
              • Pneumonia and influenza mortality has been low, but 136 influenza-associated deaths in children have been reported so far this season. This number is higher for the same time period than in every season since reporting began in 2004-05, except for the 2009 pandemic.
              • CDC estimates that so far this season there have been at least 34 million flu illnesses, 350,000 hospitalizations and 20,000 deaths from flu.
              • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.

              U.S. Virologic Surveillance

              Clinical Laboratories

              The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
              44,491 1,012,509
              10,829 (24.3%) 207,466 (20.5%)
              7,821 (72.2%) 102,650 (49.5%)
              3,008 (27.8%) 104,816 (50.5%)
              INFLUENZA Virus Isolated
              View Chart Data | View Full Screen Public Health Laboratories

              The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
              1,594 67,098
              953 37,739
              692 (72.6%) 20,452 (54.2%)
              596 (95.2%) 18,205 (92.0%)
              30 (4.8%) 1,583 (8.0%)
              66 664
              261 (27.4%) 17,287 (45.8%)
              0 (0.0%) 213 (1.6%)
              207 (100%) 13,265 (98.4%)
              54 3,809
              While influenza B/Victoria viruses predominated earlier in the season, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses. For the season, A(H1N1)pdm09 viruses are the predominant virus. The predominant virus varies by region. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.

              The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among children and young adults less than 25 years, while A viruses are the most commonly reported influenza viruses among persons 25 years and older. In the most recent three weeks, influenza A viruses are the most commonly reported influenza viruses in all but the school aged children and young adults (5-24 years old). INFLUENZA Virus Isolated
              View Chart Data | View Full Screen

              Additional virologic surveillance information for current and past seasons:
              Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
              Influenza Virus Characterization

              CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza viruses. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people. Interim estimates of 2019-2020 flu vaccine effectiveness have been released.

              CDC genetically characterized 1,903 influenza viruses collected in the U.S. from September 29, 2019, to February 29, 2020.
              645
              6B.1A 645 (100%)
              425
              3C.2a 402 (94.6%) 2a1 402 (94.6%)
              2a2 0
              2a3 0
              2a4 0
              3C.3a 23 (5.4%) 3a 23 (5.4%)
              754
              V1A 754 (100%) V1A 0
              V1A.1 53 (7.0%)
              V1A.3 701 (93.0%)
              79
              Y3 79 (100%)
              CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 363 influenza viruses collected in the United States from September 29, 2019, to February 29, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

              Influenza A Viruses
              • A (H1N1)pdm09: 131 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and 113 (86.3%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines.
              • A (H3N2): 76 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 31 (40.8%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.



              Influenza B Viruses
              • B/Victoria: 146 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 95 (65.1%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
              • B/Yamagata: 10 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 10 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.




              CDC also assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
              1,884 643 418 744 79
              1 (0.1%) (0.0%) (0.0%) 1 (0.1%) (0.0%)
              4 (0.2%) 4 (0.6%) (0.0%) (0.0%) (0.0%)
              1,884 643 418 744 79
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              5 (0.3%) 4 (0.6%) (0.0%) 1 (0.1%) (0.0%)
              1,884 643 418 744 79
              2 (0.1%) (0.0%) (0.0%) 2 (0.3%) (0.0%)
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              2,039 663 502 792 82
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              *Six influenza viruses showed reduced or highly reduced inhibition by at least one neuraminidase inhibitor. Four A(H1N1)pdm09 viruses showed highly reduced inhibition to oseltamivir and peramivir while showing normal inhibition to zanamivir. In addition, one B/Victoria virus showed highly reduced inhibition to peramivir and reduced inhibition to oseltamivir and zanamivir, while another influenza B/Victoria virus showed reduced inhibition to zanamivir.


              A total of 515 additional viruses (211 A(H1N1)pdm09, 32 A(H3N2), and 272 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Three (1.4%) of the 211 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase that confers resistance to oseltamivir and potential resistance to peramivir. No markers of resistance to neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.

              Outpatient Illness Surveillance

              ILINet

              Nationwide during week 9, 5.3% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%. national levels of ILI and ARI
              View Chart Data (current season only) | View Full Screen

              On a regional level, the percentage of outpatient visits for ILI ranged from 3.9% to 8.7% during week 9. All regions reported a percentage of outpatient visits for ILI above their region-specific baselines. ILI Activity Map

              Data collected in ILINet are used to produce a measure of ILI activity* by state.

              During week 9, the following ILI activity levels were experienced:
              • High – New York City, Puerto Rico, and 40 states (Alabama, Arkansas, California, Colorado, Connecticut, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
              • Moderate – seven states (Alaska, Delaware, Hawaii, Michigan, Nevada, New Hampshire, and South Dakota)
              • Low - one state (Idaho)
              • Minimal - the District of Columbia and two states (Arizona and Florida)
              • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

              *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.


              Additional information about medically attended visits for ILI for current and past seasons:
              Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


              Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

              The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.

              During week 9, the following influenza activity was reported:
              • Widespread – Puerto Rico and 48 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin, and Wyoming)
              • Regional – two states (Hawaii and Oregon)
              • Local – the District of Columbia
              • Sporadic – the U.S. Virgin Islands
              • Guam did not report.

              Additional geographic spread surveillance information for current and past seasons:
              Surveillance Methods | FluView Interactive

              Influenza-Associated Hospitalizations

              The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.

              A total of 16,819 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and February 29, 2020; 11,707 (69.6%) were associated with influenza A virus, 5,020 (29.8%) with influenza B virus, 51 (0.3%) with influenza A virus and influenza B virus co-infection, and 41 (0.2%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 3,183 (94.2%) were A(H1N1)pdm09 virus and 196 (5.8%) were A(H3N2).

              The overall cumulative hospitalization rate was 57.9 per 100,000 population which is similar to what has been seen during recent previous influenza seasons at this time of year. Rates in school aged children and young adults are higher than at this time in recent seasons, and rates among children 0-4 years old are now the highest CDC has on record at this point in the season, surpassing rates reported during the second wave of the 2009 H1N1 pandemic.

              Click on graph to launch interactive tool View Full Screen

              The highest rate of hospitalization is among adults aged ≥ 65, followed by children aged 0-4 years and adults aged 50-64 years.
              Overall 57.9
              0-4 years 84.9
              5-17 years 21.6
              18-49 years 31.2
              50-64 years 76.1
              65+ years 147.5

              Among 2,528 hospitalized adults with information on underlying medical conditions, 91.9% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 443 hospitalized children with information on underlying medical conditions, 48.5% had at least one underlying medical condition; the most commonly reported was asthma. Among 427 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 25.8% were pregnant.

              Click on graph to launch interactive tool2 View Full Screen

              Additional hospitalization surveillance information for current and past seasons and additional age groups:
              Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


              Pneumonia and Influenza (P&I) Mortality Surveillance

              Based on National Center for Health Statistics (NCHS) mortality surveillance data available on March 5, 2020, 6.9% of the deaths occurring during the week ending February 22, 2020 (week 8) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 8. INFLUENZA Virus Isolated
              View Chart Data | View Full Screen

              Additional pneumonia and influenza mortality surveillance information for current and past seasons:
              Surveillance Methods | FluView Interactive


              Influenza-Associated Pediatric Mortality

              11 influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 51 and 9 (the weeks ending December 21, 2019 and February 29, 2020) were reported to CDC during week 9. Six were associated with influenza B viruses, and none had a lineage determined. Five were associated with influenza A viruses, and one was subtyped and was an A(H1N1)pdm09 virus.

              Of the 136 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
              • 93 deaths were associated with influenza B viruses, and 18 had a lineage determined; all were B/Victoria viruses.
              • 43 deaths were associated with influenza A viruses, and 24 were subtyped; 23 were A(H1N1)pdm09 viruses, and one was an A(H3) virus.
              Click on image to launch interactive tool
              View Full Screen

              Additional pediatric mortality surveillance information for current and past seasons:
              Surveillance Methods | FluView Interactive



              Additional National and International Influenza Surveillance Information

              FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

              National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html

              U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information



              World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.

              WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).

              Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.

              Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/

              Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports






              Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.


              An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.

              --------------------------------------------------------------------------------



              Page last reviewed: March 6, 2020, 11:00 AM
              Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)Seasonal Influenza (Flu)What CDC Does
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              The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

              Comment


              • #22
                Weekly U.S. Influenza Surveillance Report



                Note: The COVID-19 outbreak unfolding in the United States may affect healthcare seeking behavior which in turn would impact data from ILINet.

                Key Updates for Week 10, ending March 7, 2020

                Flu activity as reported by clinical laboratories remains high but decreased for the fourth week in a row; however, influenza-like illness activity increased slightly. Severity indicators remain moderate to low overall, but hospitalization rates differ by age group, with high rates among children and young adults. Viruses

                Clinical Labs
                The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 26.1% last week to 21.5% this week.

                Public Health Labs
                Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.

                Virus Characterization
                Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report. Illness

                Outpatient Illness: ILINet
                Visits to health care providers for influenza-like illness (ILI) increased slightly from 5.1% last week to 5.2% this week. All regions remain above their baselines.

                Outpatient Illness: ILINet Activity Map
                Flu Activity & Surveillance

                The number of jurisdictions experiencing high ILI activity increased slightly from 42 last week to 43 this week.

                Geographic Spread
                Spread Map 10

                The number of jurisdictions reporting regional or widespread influenza activity decreased from 51 last week to 50 this week. Severe Disease

                Hospitalizations
                The overall cumulative hospitalization rate for the season increased to 61.6 per 100,000.

                P&I Mortality
                The percentage of deaths attributed to pneumonia and influenza is 7.1%, below the epidemic threshold of 7.3%.

                Pediatric Deaths
                8 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 144.

                All data are preliminary and may change as more reports are received.

                A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.

                Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

                Key Points
                • Clinical laboratory data remain elevated but decreased for the fourth week in a row while ILI activity increased slightly. The largest increases in ILI activity occurred in areas of the country where COVID-19 is most prevalent. More people may be seeking care for respiratory illness than usual at this time.
                • Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season. Previously, influenza B/Victoria viruses predominated nationally.
                • Laboratory confirmed influenza associated hospitalization rates for the overall U.S. population remain moderate compared to recent seasons, but rates for children 0-4 years and adults 18-49 years are now the highest CDC has on record for these age groups, surpassing rates reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children (5-17 years) are higher than any recent regular season but remain lower than rates experienced by this age group during the pandemic.
                • Pneumonia and influenza mortality has been low, but 144 influenza-associated deaths in children have been reported so far this season. This number is higher for the same time period than in every season since reporting began in 2004-05, except for the 2009 pandemic.
                • CDC estimates that so far this season there have been at least 36 million flu illnesses, 370,000 hospitalizations and 22,000 deaths from flu.
                • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.

                U.S. Virologic Surveillance

                Clinical Laboratories

                The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
                43,868 1,073,976
                9,413 (21.5%) 222,552 (20.7%)
                7,294 (77.5%) 114,029 (51.2%)
                2,119 (22.5%) 108,523 (48.8%)
                INFLUENZA Virus Isolated
                View Chart Data | View Full Screen Public Health Laboratories

                The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
                1,513 70,363
                744 39,644
                575 (77.3%) 21,880 (55.2%)
                466 (93.4%) 19,537 (92.2%)
                33 (6.6%) 1,647 (7.8%)
                76 696
                169 (22.7%) 17,764 (44.8%)
                0 (0.0%) 219 (1.6%)
                130 (100%) 13,694 (98.4%)
                39 3,851
                While influenza B/Victoria viruses predominated earlier in the season, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses nationally and in all surveillance regions. For the season, A(H1N1)pdm09 viruses are the predominant virus nationally. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.

                The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among children and young adults less than 25 years, while A viruses are the most commonly reported influenza viruses among persons 25 years and older. In the most recent three weeks, influenza A viruses are the most commonly reported influenza viruses in all age groups. INFLUENZA Virus Isolated
                View Chart Data | View Full Screen

                Additional virologic surveillance information for current and past seasons:
                Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data
                Influenza Virus Characterization

                CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza viruses. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people. Interim estimates of 2019-2020 flu vaccine effectiveness have been released.

                CDC genetically characterized 2,065 influenza viruses collected in the U.S. from September 29, 2019, to March 7, 2020.
                720
                6B.1A 720 (100%)
                454
                3C.2a 428 (94.3%) 2a1 428 (94.3%)
                2a2 0
                2a3 0
                2a4 0
                3C.3a 26 (5.7%) 3a 26 (5.7%)
                807
                V1A 807 (100%) V1A 0
                V1A.1 56 (6.9%)
                V1A.3 751 (93.1%)
                84
                Y3 84 (100%)
                CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 403 influenza viruses collected in the United States from September 29, 2019, to March 7, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.

                Influenza A Viruses
                • A (H1N1)pdm09: 153 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and 123 (80.4%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines. The decrease in the percent of A(H1N1)pdm09 viruses similar to A/Brisbane/02/2018 is due to some of the recent viruses selected for testing having a single amino acid change that is antigenically distinguishable in antigenic assays using ferret sera. Similar viruses were observed last season as well and these represented a small proportion of virus circulating. We have observed an increase in the proportion of H1N1pdm09 viruses with this change late in the US season.
                • A (H3N2): 76 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 31 (40.8%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.



                Influenza B Viruses
                • B/Victoria: 146 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 95 (65.1%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
                • B/Yamagata: 28 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 28 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.




                CDC also assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
                2,042 715 444 799 84
                1 (0.04%) (0.0%) (0.0%) 1 (0.1%) (0.0%)
                4 (0.2%) 4 (0.6%) (0.0%) (0.0%) (0.0%)
                2,042 715 444 799 84
                (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                5 (0.2%) 4 (0.6%) (0.0%) 1 (0.1%) (0.0%)
                2,042 715 444 799 84
                2 (0.1%) (0.0%) (0.0%) 2 (0.3%) (0.0%)
                (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                2,194 735 529 843 87
                (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                *Six influenza viruses showed reduced or highly reduced inhibition by at least one neuraminidase inhibitor. Four A(H1N1)pdm09 viruses showed highly reduced inhibition to oseltamivir and peramivir while showing normal inhibition to zanamivir. In addition, one B/Victoria virus showed highly reduced inhibition to peramivir and reduced inhibition to oseltamivir and zanamivir, while another influenza B/Victoria virus showed reduced inhibition to zanamivir.


                A total of 556 additional viruses (211 A(H1N1)pdm09, 32 A(H3N2), and 313 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Three (1.4%) of the 211 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase and showed highly reduced inhibition by oseltamivir and peramivir. No molecular markers associated with reduced or highly reduced inhibition by neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.

                Outpatient Illness Surveillance

                ILINet

                Nationwide during week 10, 5.2% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%. national levels of ILI and ARI
                View Chart Data (current season only) | View Full Screen

                On a regional level, the percentage of outpatient visits for ILI ranged from 3.9% to 8.4% during week 10. All regions reported a percentage of outpatient visits for ILI above their region-specific baselines. Regions 2, 7, and 10 reported the greatest increases in ILI relative to their baselines. Clinical laboratories in regions 2 and 10 reported a decrease in influenza virus circulation; however, these are areas of the country where COVID-19 is most prevalent and more people may be seeking care for respiratory illness than usual at this time. The ILI increase in region 7 appears most likely due to low reporting. ILI Activity Map

                Data collected in ILINet are used to produce a measure of ILI activity* by state.

                During week 10, the following ILI activity levels were experienced:
                • High – New York City, Puerto Rico, and 41 states (Alabama, Arkansas, California, Colorado, Connecticut, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, and Wisconsin)
                • Moderate – two states (New Hampshire and Ohio)
                • Low - the District of Columbia and four states (Alaska, Delaware, Idaho, and Nevada)
                • Minimal - three states (Arizona, Florida, and Wyoming)
                • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.


                Additional information about medically attended visits for ILI for current and past seasons:
                Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


                Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.

                During week 10, the following influenza activity was reported:
                • Widespread – Puerto Rico and 48 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming)
                • Regional – one state (Oregon)
                • Local – the District of Columbia and one state (Hawaii)
                • Sporadic – the U.S. Virgin Islands
                • Guam did not report.

                Additional geographic spread surveillance information for current and past seasons:
                Surveillance Methods | FluView Interactive

                Influenza-Associated Hospitalizations

                The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.

                A total of 17,889 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and March 7, 2020; 12,652 (70.7%) were associated with influenza A virus, 5,140 (28.7%) with influenza B virus, 50 (0.3%) with influenza A virus and influenza B virus co-infection, and 47 (0.3%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 3,391 (94.2%) were A(H1N1)pdm09 virus and 207 (5.8%) were A(H3N2).

                The overall cumulative hospitalization rate was 61.6 per 100,000 population which is higher than all recent seasons at this time of year except for the 2017-18 season. Rates in children 0-4 years old and adults 18-49 years old are now the highest CDC has on record for these age groups, surpassing the rate reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children are higher than any recent regular season but lower than rates during the pandemic.

                Click on graph to launch interactive tool View Full Screen

                The highest rate of hospitalization is among adults aged ≥ 65, followed by children aged 0-4 years and adults aged 50-64 years.
                Overall 61.6
                0-4 years 88.9
                5-17 years 22.6
                18-49 years 32.8
                50-64 years 80.8
                65+ years 159.4

                Among 2,867 hospitalized adults with information on underlying medical conditions, 92.3% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 472 hospitalized children with information on underlying medical conditions, 48.3% had at least one underlying medical condition; the most commonly reported was asthma. Among 477 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 27.5% were pregnant.

                Click on graph to launch interactive tool2 View Full Screen

                Additional hospitalization surveillance information for current and past seasons and additional age groups:
                Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


                Pneumonia and Influenza (P&I) Mortality Surveillance

                Based on National Center for Health Statistics (NCHS) mortality surveillance data available on March 12, 2020, 7.1% of the deaths occurring during the week ending February 29, 2020 (week 9) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 9. INFLUENZA Virus Isolated
                View Chart Data | View Full Screen

                Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                Surveillance Methods | FluView Interactive


                Influenza-Associated Pediatric Mortality

                Eight influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 6 and 10 (the weeks ending February 8, 2020 and March 7, 2020) were reported to CDC during week 10. Three were associated with influenza B viruses; one had a lineage determined and was a B/Victoria virus. Five were associated with influenza A viruses, and three were subtyped; all were A(H1N1)pdm09 viruses.

                Of the 144 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
                • 96 deaths were associated with influenza B viruses, and 20 had a lineage determined; all were B/Victoria viruses.
                • 48 deaths were associated with influenza A viruses, and 27 were subtyped; 26 were A(H1N1)pdm09 viruses, and one was an A(H3) virus.
                Click on image to launch interactive tool
                View Full Screen

                Additional pediatric mortality surveillance information for current and past seasons:
                Surveillance Methods | FluView Interactive



                Additional National and International Influenza Surveillance Information

                FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm

                National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html

                U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information



                World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.

                WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).

                Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.

                Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/

                Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports






                Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.


                An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.

                --------------------------------------------------------------------------------



                Page last reviewed: March 13, 2020, 11:00 AM
                Content source: Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)Seasonal Influenza (Flu)What CDC Does
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                • #23
                  Week 11: https://www.cdc.gov/flu/weekly/

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                  • #24

                    Weekly U.S. Influenza Surveillance Report


                    Note: The COVID-19 outbreak unfolding in the United States may affect healthcare seeking behavior which in turn would impact data from ILINet.


                    Key Updates for Week 12, ending March 21, 2020
                    Laboratory confirmed flu activity as reported by clinical laboratories continues to decrease; however, influenza-like illness activity is increasing. Influenza severity indicators remain moderate to low overall, but hospitalization rates differ by age group, with high rates among children and young adults.




                    Viruses



                    Clinical Labs
                    The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 14.9% last week to 6.9% this week.


                    Public Health Labs
                    Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.


                    Virus Characterization
                    Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report.



                    Illness

                    Outpatient Illness: ILINet
                    Visits to health care providers for influenza-like illness (ILI) increased from 5.6% last week to 6.4% this week. All regions are above their baselines.



                    Outpatient Illness: ILINet Activity Map

                    The number of jurisdictions experiencing high ILI activity decreased from 40 last week to 37 this week.


                    Geographic Spread

                    The number of jurisdictions reporting regional or widespread influenza activity decreased from 50 last week to 49 this week.



                    Severe Disease



                    Hospitalizations
                    The overall cumulative hospitalization rate for the season increased to 67.3 per 100,000.


                    P&I Mortality
                    The percentage of deaths attributed to pneumonia and influenza is 7.4%, above the epidemic threshold of 7.3%.


                    Pediatric Deaths
                    6 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 155.



                    All data are preliminary and may change as more reports are received.
                    A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.
                    Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.
                    Key Points
                    • Nationally, the percent of laboratory specimens testing positive for influenza at clinical laboratories continued to decrease while ILI activity continued to increase. More people are seeking care for respiratory illness due to the ongoing COVID-19 pandemic.
                    • Nationally, influenza A(H1N1)pdm09 viruses are the most commonly reported influenza viruses this season. Previously, influenza B/Victoria viruses predominated nationally.
                    • Laboratory confirmed influenza-associated hospitalization rates for the U.S. population overall are higher than most recent seasons and rates for children 0-4 years and adults 18-49 years are the highest CDC has on record for these age groups, surpassing rates reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children (5-17 years) are higher than any recent regular season but remain lower than rates experienced by this age group during the pandemic.
                    • Pneumonia and influenza mortality levels have been low, but 155 influenza-associated deaths in children have been reported so far this season. This number is higher than recorded at the same time in every season since reporting began in 2004-05, except for the 2009 pandemic.
                    • CDC estimates that so far this season there have been at least 39 million flu illnesses, 400,000 hospitalizations and 24,000 deaths from flu.
                    • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.



                    U.S. Virologic Surveillance

                    Clinical Laboratories

                    The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
                    51,570 1,208,294
                    3,581 (6.9%) 242,330 (20.1%)
                    2,748 (76.7%) 128,676 (53.1 %)
                    833 (23.3%) 113,654 (46.9%)

                    View Chart Data | View Full ScreenPublic Health Laboratories

                    The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
                    2,139 78,778
                    219 42,510
                    181 (82.6%) 24,087 (56.7%)
                    147 (91.9%) 21,583 (92.5%)
                    13 (8.1%) 1,744 (7.5%)
                    21 760
                    38 (17.4%) 18,423 (43.3%)
                    0 (0.0%) 231 (1.6%)
                    28 (100%) 14,077 (98.4%)
                    10 4,115
                    While influenza B/Victoria viruses predominated earlier in the season, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses nationally and in all surveillance regions. For the season, A(H1N1)pdm09 viruses are the predominant virus nationally. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.
                    The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among persons 5-24 years, while influenza A viruses are the most commonly reported influenza viruses among persons 0-4 years and 25 years and older. In the most recent three weeks, influenza A viruses are the most commonly reported influenza viruses in all age groups.

                    View Chart Data | View Full Screen
                    Additional virologic surveillance information for current and past seasons:
                    Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data

                    Influenza Virus Characterization

                    CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza viruses. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people. Interim estimates of 2019-2020 flu vaccine effectiveness have been released.
                    CDC genetically characterized 2,336 influenza viruses collected in the U.S. from September 29, 2019, to March 21, 2020.
                    840
                    6B.1A 840 (100%)
                    497
                    3C.2a 467 (94.0%) 2a1 467 (94.0%)
                    2a2 0
                    2a3 0
                    2a4 0
                    3C.3a 30 (6.0%) 3a 30 (6.0%)
                    909
                    V1A 909 (100%) V1A 0
                    V1A.1 60 (6.6%)
                    V1A.3 849 (93.4%)
                    90
                    Y3 90 (100%)
                    CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 471 influenza viruses collected in the United States from September 29, 2019, to March 21, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.
                    Influenza A Viruses
                    • A (H1N1)pdm09: 177 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and 143 (80.8%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines. The decrease in the percent of A(H1N1)pdm09 viruses similar to A/Brisbane/02/2018 is due to some of the recent viruses selected for testing having a single amino acid change that is antigenically distinguishable in antigenic assays using ferret sera. Similar viruses were observed last season as well and these represented a small proportion of virus circulating. We have observed an increase in the proportion of H1N1pdm09 viruses with this change late in the US season.
                    • A (H3N2): 86 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 40 (46.5%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.

                    Influenza B Viruses
                    • B/Victoria: 180 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 112 (62.2%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
                    • B/Yamagata: 28 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 28 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.


                    CDC also assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
                    2,309 831 488 900 90
                    1 (0.0%) (0.0%) (0.0%) 1 (0.1%) (0.0%)
                    4 (0.2%) 4 (0.5%) (0.0%) (0.0%) (0.0%)
                    2,309 831 488 900 90
                    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                    5 (0.2%) 4 (0.5%) (0.0%) 1 (0.1%) (0.0%)
                    2,309 831 488 900 90
                    2 (0.1%) (0.0%) (0.0%) 2 (0.2%) (0.0%)
                    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                    2,467 855 573 946 93
                    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                    *Six influenza viruses showed reduced or highly reduced inhibition by at least one neuraminidase inhibitor. Four A(H1N1)pdm09 viruses showed highly reduced inhibition to oseltamivir and peramivir while showing normal inhibition to zanamivir. In addition, one B/Victoria virus showed highly reduced inhibition to peramivir and reduced inhibition to oseltamivir and zanamivir, while another influenza B/Victoria virus showed reduced inhibition to zanamivir.

                    A total of 556 additional viruses (211 A(H1N1)pdm09, 32 A(H3N2), and 313 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Three (1.4%) of the 211 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase and showed highly reduced inhibition by oseltamivir and peramivir. No molecular markers associated with reduced or highly reduced inhibition by neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.


                    Outpatient Illness Surveillance

                    ILINet

                    Nationwide during week 12, 6.4% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%.

                    View Chart Data (current season only) | View Full Screen
                    On a regional level, the percentage of outpatient visits for ILI ranged from 4.7% to 11.8% during week 12. Eight of the 10 surveillance regions reported an increase in percentage of outpatient visits for ILI, and all regions reported a percentage of outpatient visits for ILI above their region-specific baselines.
                    ILI Activity Map

                    Data collected in ILINet are used to produce a measure of ILI activity* by state.
                    During week 12, the following ILI activity levels were experienced:
                    • High – the District of Columbia, New York City, Puerto Rico, and 34 states (Alabama, California, Colorado, Connecticut, Georgia, Illinois, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Minnesota, Mississippi, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, and Wisconsin)
                    • Moderate – 10 states (Arkansas, Hawaii, Idaho, Indiana, Iowa, Missouri, Nevada, Ohio, South Dakota, and Wyoming)
                    • Low - two states (Alaska and Delaware)
                    • Minimal - four states (Arizona, Florida, New Hampshire, and Rhode Island)
                    • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                    *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.
                    Among the 37 jurisdictions with high ILI activity, ILI increased relative to the previous week in 20, remained stable in 10 and declined in 7. Thirty-four of the jurisdictions with high ILI activity also had clinical laboratory data available and in those, the percent of specimens testing positive for influenza decreased in 32 and increased in only 2.

                    Additional information about medically attended visits for ILI for current and past seasons:
                    Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


                    Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                    The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
                    During week 12, the following influenza activity was reported:
                    • Widespread – Puerto Rico and 38 states (Alabama, Colorado, Connecticut, Delaware, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Maryland, Massachusetts, Michigan, Mississippi, Missouri, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia and Wisconsin)
                    • Regional – 10 states (Arizona, Arkansas, California, Florida, Minnesota, Montana, Nebraska, North Dakota, South Dakota and Wyoming)
                    • Local – the District of Columbia and two states (Alaska and Hawaii)
                    • Sporadic – the U.S. Virgin Islands
                    • Guam did not report.

                    Additional geographic spread surveillance information for current and past seasons:
                    Surveillance Methods | FluView Interactive


                    Influenza-Associated Hospitalizations

                    The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
                    A total of 19,543 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and March 21, 2020; 14,100 (72.1%) were associated with influenza A virus, 5,335 (27.3%) with influenza B virus, 56 (0.3%) with influenza A virus and influenza B virus co-infection, and 52 (0.3%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 3,747 (94.5%) were A(H1N1)pdm09 virus and 219 (5.5%) were A(H3N2).
                    The overall cumulative hospitalization rate was 67.3 per 100,000 population, which is higher than all recent seasons at this time of year except for the 2017-18 season. Rates in children 0-4 years old and adults 18-49 years old are now the highest CDC has on record for these age groups, surpassing the rate reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children are higher than any recent regular season but lower than rates during the pandemic.

                    View Full Screen
                    The highest rate of hospitalization is among adults aged ≥ 65, followed by children aged 0-4 years and adults aged 50-64 years.
                    Overall 67.3
                    0-4 years 93.9
                    5-17 years 24.4
                    18-49 years 35.2
                    50-64 years 88.9
                    65+ years 176.8
                    Among 3,161 hospitalized adults with information on underlying medical conditions, 92.3% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 535 hospitalized children with information on underlying medical conditions, 47.7% had at least one underlying medical condition; the most commonly reported was asthma. Among 551 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 27% were pregnant.

                    View Full Screen
                    Additional hospitalization surveillance information for current and past seasons and additional age groups:
                    Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


                    Pneumonia and Influenza (P&I) Mortality Surveillance

                    Based on National Center for Health Statistics (NCHS) mortality surveillance data available on March 26, 2020, 7.4% of the deaths occurring during the week ending March 7, 2020 (week 11) were due to P&I. This percentage is above the epidemic threshold of 7.3% for week 11.

                    View Chart Data | View Full Screen
                    Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                    Surveillance Methods | FluView Interactive


                    Influenza-Associated Pediatric Mortality

                    Six influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 6 and 11 (the weeks ending February 8, 2020 and March 14, 2020) were reported to CDC during week 12. Three were associated with influenza A viruses, and one was subtyped as an A(H1N1)pdm09 virus. Three were associated with influenza B viruses and all were B/Victoria viruses.
                    Of the 155 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
                    • 99 deaths were associated with influenza B viruses, and 24 had a lineage determined; all were B/Victoria viruses.
                    • 56 deaths were associated with influenza A viruses, and 31 were subtyped; 30 were A(H1N1)pdm09 viruses, and one was an A(H3) virus.


                    View Full Screen
                    Additional pediatric mortality surveillance information for current and past seasons:
                    Surveillance Methods | FluView Interactive



                    Additional National and International Influenza Surveillance Information


                    FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
                    National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html
                    U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information
                    World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
                    WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
                    Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
                    Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
                    Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports




                    Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.
                    An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.
                    --------------------------------------------------------------------------------


















                    Seasonal Influenza (Flu)What CDC Does

                    email_03Get Email Updates
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                    Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.

                    Twitter: @RonanKelly13
                    The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

                    Comment


                    • #25

                      Weekly U.S. Influenza Surveillance Report


                      Note: The COVID-19 pandemic is affecting healthcare seeking behavior. The number of persons and their reasons for seeking care in the outpatient and ED settings is changing. These changes impact data from ILINet in ways that are difficult to differentiate from changes in illness levels, therefore ILINet data should be interpreted with caution.


                      Key Updates for Week 13, ending March 28, 2020
                      Laboratory confirmed flu activity as reported by clinical laboratories continues to decrease sharply and is now low. Influenza-like illness activity, while lower than last week, is still elevated. Influenza severity indicators remain moderate to low overall, but hospitalization rates differ by age group, with high rates among children and young adults.




                      Viruses



                      Clinical Labs
                      The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 7.3% last week to 2.1% this week.


                      Public Health Labs
                      Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.


                      Virus Characterization
                      Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report.



                      Illness

                      Outpatient Illness: ILINet
                      Visits to health care providers for influenza-like illness (ILI) decreased from 6.3% last week to 5.4% this week. All regions are above their baselines.



                      Outpatient Illness: ILINet Activity Map

                      The number of jurisdictions experiencing high ILI activity decreased from 37 last week to 31 this week.


                      Geographic Spread

                      The number of jurisdictions reporting regional or widespread influenza activity decreased from 49 last week to 41 this week.



                      Severe Disease



                      Hospitalizations
                      The overall cumulative hospitalization rate for the season increased to 67.9 per 100,000.


                      P&I Mortality
                      The percentage of deaths attributed to pneumonia and influenza is 8.2%, above the epidemic threshold of 7.2%.


                      Pediatric Deaths
                      7 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 162.



                      All data are preliminary and may change as more reports are received.
                      A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.
                      Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.
                      Key Points
                      • Nationally, the percent of laboratory specimens testing positive for influenza at clinical laboratories continued to decrease and is now low.
                      • ILI activity decreased nationally but remains elevated.
                      • Recent changes in healthcare seeking behavior, including increasing use of telemedicine and recommendations to limit emergency department (ED) visits to severe illness, as well as increasing levels of social distancing, are affecting the number of persons with ILI and their reasons for seeking care in outpatient and ED settings.
                      • Laboratory confirmed influenza-associated hospitalization rates for the U.S. population overall are higher than most recent seasons and rates for children 0-4 years and adults 18-49 years are the highest CDC has on record for these age groups, surpassing rates reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children (5-17 years) are higher than any recent regular season but remain lower than rates experienced by this age group during the pandemic.
                      • The percent of deaths associated with pneumonia and influenza is above the epidemic threshold. The increase is due to an increase in pneumonia deaths rather than influenza deaths and may be associated with COVID-19.
                      • 162 influenza-associated deaths in children have been reported so far this season. This number is higher than recorded at the same time in every season since reporting began in 2004-05, except for the 2009 pandemic.
                      • CDC estimates that so far this season there have been at least 39 million flu illnesses, 400,000 hospitalizations and 24,000 deaths from flu.
                      • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.



                      U.S. Virologic Surveillance

                      Clinical Laboratories

                      The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
                      30,656 1,270,617
                      633 (2.1%) 246,842 (19.4%)
                      457 (72.2%) 131,861 (53.4 %)
                      176 (27.8%) 114,981 (46.6%)

                      View Chart Data | View Full ScreenPublic Health Laboratories

                      The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
                      924 80,427
                      75 43,174
                      54 (72.0%) 24,579 (56.9%)
                      44 (91.7%) 22,107 (92.6%)
                      4 (8.3%) 1,764 (7.4%)
                      6 708
                      21 (28.0%) 18,595 (43.1%)
                      2 (20.0%) 235 (1.6%)
                      8 (80.0%) 14,165 (98.4%)
                      11 4,195
                      While influenza B/Victoria viruses predominated earlier in the season, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses nationally and in all surveillance regions. For the season, A(H1N1)pdm09 viruses are the predominant virus nationally. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.
                      The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among persons 5-24 years, while influenza A viruses are the most commonly reported influenza viruses among persons 0-4 years and 25 years and older. In the most recent three weeks, influenza A viruses are the most commonly reported influenza viruses in all age groups.

                      View Chart Data | View Full Screen
                      Additional virologic surveillance information for current and past seasons:
                      Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data

                      Influenza Virus Characterization

                      CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza viruses. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people. Interim estimates of 2019-2020 flu vaccine effectiveness have been released.
                      CDC genetically characterized 2,350 influenza viruses collected in the U.S. from September 29, 2019, to March 28, 2020.
                      852
                      6B.1A 852 (100%)
                      498
                      3C.2a 468 (94.0%) 2a1 468 (94.0%)
                      2a2 0
                      2a3 0
                      2a4 0
                      3C.3a 30 (6.0%) 3a 30 (6.0%)
                      910
                      V1A 910 (100%) V1A 0
                      V1A.1 60 (6.6%)
                      V1A.3 850 (93.4%)
                      90
                      Y3 90 (100%)
                      CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 521 influenza viruses collected in the United States from September 29, 2019, to March 28, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.
                      Influenza A Viruses
                      • A (H1N1)pdm09: 207 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and 171 (82.6%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines. The decrease in the percent of A(H1N1)pdm09 viruses similar to A/Brisbane/02/2018 is due to some of the recent viruses selected for testing having a single amino acid change that is antigenically distinguishable in antigenic assays using ferret sera. Similar viruses were observed last season as well and these represented a small proportion of virus circulating. We have observed an increase in the proportion of H1N1pdm09 viruses with this change late in the US season.
                      • A (H3N2): 86 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 40 (46.5%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.

                      Influenza B Viruses
                      • B/Victoria: 180 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 112 (62.2%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
                      • B/Yamagata: 48 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 48 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.


                      CDC also assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
                      2,361 851 494 924 92
                      1 (0.0%) (0.0%) (0.0%) 1 (0.1%) (0.0%)
                      4 (0.2%) 4 (0.5%) (0.0%) (0.0%) (0.0%)
                      2,361 851 494 924 92
                      (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                      5 (0.2%) 4 (0.5%) (0.0%) 1 (0.1%) (0.0%)
                      2,361 851 494 924 92
                      2 (0.1%) (0.0%) (0.0%) 2 (0.2%) (0.0%)
                      (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                      2,476 864 573 946 93
                      (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                      *Six influenza viruses showed reduced or highly reduced inhibition by at least one neuraminidase inhibitor. Four A(H1N1)pdm09 viruses showed highly reduced inhibition to oseltamivir and peramivir while showing normal inhibition to zanamivir. In addition, one B/Victoria virus showed highly reduced inhibition to peramivir and reduced inhibition to oseltamivir and zanamivir, while another influenza B/Victoria virus showed reduced inhibition to zanamivir.

                      A total of 556 additional viruses (211 A(H1N1)pdm09, 32 A(H3N2), and 313 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Three (1.4%) of the 211 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase and showed highly reduced inhibition by oseltamivir and peramivir. No molecular markers associated with reduced or highly reduced inhibition by neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.


                      Outpatient Illness Surveillance

                      ILINet

                      Nationwide during week 13, 5.4% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%.

                      View Chart Data (current season only) | View Full Screen
                      On a regional level, the percentage of outpatient visits for ILI ranged from 3.7% to 12.2% during week 13. Only region 2 reported an increase in percentage of outpatient visits for ILI, but all regions reported a percentage of outpatient visits for ILI above their region-specific baselines.
                      ILI Activity Map

                      Data collected in ILINet are used to produce a measure of ILI activity* by state.
                      During week 13, the following ILI activity levels were experienced:
                      • High – the District of Columbia, New York City, Puerto Rico, and 28 states (Alabama, California, Colorado, Connecticut, Georgia, Illinois, Kansas, Louisiana, Maryland, Massachusetts, Minnesota, Mississippi, Montana, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Vermont, Virginia, Washington, and Wisconsin)
                      • Moderate – five states (Idaho, Maine, Michigan, Nebraska, and Utah)
                      • Low - five states (Arkansas, Kentucky, Missouri, Ohio, and South Dakota)
                      • Minimal - 12 states (Alaska, Arizona, Delaware, Florida, Hawaii, Indiana, Iowa, Nevada, New Hampshire, Rhode Island, West Virginia, and Wyoming)
                      • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                      *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.
                      Among the 31 jurisdictions with high ILI activity, ILI increased relative to the previous week in one, remained stable in 30 and declined in 27. Twenty-seven of the jurisdictions with high ILI activity also had clinical laboratory data available and in those, the percent of specimens testing positive for influenza decreased in all but one.

                      Additional information about medically attended visits for ILI for current and past seasons:
                      Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


                      Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                      The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
                      During week 13, the following influenza activity was reported:
                      • Widespread – Puerto Rico and 22 states (Alabama, Alaska, Connecticut, Georgia, Idaho, Indiana, Kansas, Louisiana, Maryland, Massachusetts, Nevada, New Hampshire, New York, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee, Vermont, Virginia, Washington and Wisconsin)
                      • Regional – 18 states (Arizona, Arkansas, Colorado, Illinois, Iowa, Kentucky, Maine, Michigan, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, Oregon, Texas, Utah and Wyoming)
                      • Local – the District of Columbia and seven states (Florida, Hawaii, Minnesota, North Dakota, Pennsylvania, South Dakota and Wyoming)
                      • Sporadic – the U.S. Virgin Islands and three states (California, Delaware and Rhode Island)
                      • Guam did not report.

                      Additional geographic spread surveillance information for current and past seasons:
                      Surveillance Methods | FluView Interactive


                      Influenza-Associated Hospitalizations

                      The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
                      A total of 19,713 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and March 28, 2020; 14,244 (72.3%) were associated with influenza A virus, 5,357 (27.2%) with influenza B virus, 59 (0.3%) with influenza A virus and influenza B virus co-infection, and 53 (0.3%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 3,771 (94.4%) were A(H1N1)pdm09 virus and 221 (5.5%) were A(H3N2).
                      The overall cumulative hospitalization rate was 67.9 per 100,000 population, which is higher than all recent seasons at this time of year except for the 2017-18 season. Rates in children 0-4 years old and adults 18-49 years old are now the highest CDC has on record for these age groups, surpassing the rate reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children are higher than any recent regular season but lower than rates during the pandemic.

                      View Full Screen
                      The highest rate of hospitalization is among adults aged ≥ 65, followed by children aged 0-4 years and adults aged 50-64 years.
                      Overall 67.9
                      0-4 years 93.9
                      5-17 years 24.6
                      18-49 years 35.5
                      50-64 years 89.7
                      65+ years 178.8
                      Among 3,271 hospitalized adults with information on underlying medical conditions, 92.1% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 552 hospitalized children with information on underlying medical conditions, 48.4% had at least one underlying medical condition; the most commonly reported was asthma. Among 556 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 27.2% were pregnant.

                      View Full Screen
                      Additional hospitalization surveillance information for current and past seasons and additional age groups:
                      Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


                      Pneumonia and Influenza (P&I) Mortality Surveillance

                      Based on National Center for Health Statistics (NCHS) mortality surveillance data available on March 26, 2020, 8.2% of the deaths occurring during the week ending March 21, 2020 (week 12) were due to P&I. This percentage is above the epidemic threshold of 7.2% for week 12.

                      View Chart Data | View Full Screen
                      While the percent of all deaths due to P&I has increased during weeks 9-12 (7.4-8.2%), the percent of all deaths with Influenza listed as a cause have decreased (from 1.0% to 0.8%) over this same time period. The increase in pneumonia deaths during this time period are likely associated with COVID-19 rather than influenza.

                      Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                      Surveillance Methods | FluView Interactive


                      Influenza-Associated Pediatric Mortality

                      Seven influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 5 and 13 (the weeks ending February 1, 2020 and March 28, 2020) were reported to CDC during week 13. Four were associated with influenza A viruses, and all were subtyped as A(H1N1)pdm09 viruses. Three were associated with influenza B viruses, and one was subtyped as a B/Victoria virus.
                      Of the 162 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
                      • 102 deaths were associated with influenza B viruses, and 25 had a lineage determined; all were B/Victoria viruses.
                      • 60 deaths were associated with influenza A viruses, and 35 were subtyped; 34 were A(H1N1)pdm09 viruses, and one was an A(H3) virus.


                      View Full Screen
                      Additional pediatric mortality surveillance information for current and past seasons:
                      Surveillance Methods | FluView Interactive



                      Additional National and International Influenza Surveillance Information


                      FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
                      National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html
                      U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information
                      World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
                      WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
                      Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
                      Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
                      Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports




                      Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.
                      An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.
                      --------------------------------------------------------------------------------


















                      Seasonal Influenza (Flu)What CDC Does

                      email_03Get Email Updates
                      To receive weekly email updates about Seasonal Flu, enter your email address:
                      Email Address

                      What's this?
                      Submit




                      Influenza Types



                      Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.
                      Twitter: @RonanKelly13
                      The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

                      Comment


                      • #26

                        Weekly U.S. Influenza Surveillance Report



                        Note: The COVID-19 pandemic is affecting healthcare seeking behavior. The number of persons and their reasons for seeking care in the outpatient and ED settings is changing. These changes impact data from ILINet in ways that are difficult to differentiate from changes in illness levels, therefore ILINet data should be interpreted with caution.


                        Key Updates for Week 14, ending April 4, 2020
                        Laboratory confirmed flu activity as reported by clinical laboratories continues to decrease sharply and is now low. Influenza-like illness activity, while lower than last week, is still elevated. Influenza severity indicators remain moderate to low overall, but hospitalization rates differ by age group, with high rates among children and young adults.




                        Viruses



                        Clinical Labs
                        The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 2.1% last week to 0.8% this week.


                        Public Health Labs
                        Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.


                        Virus Characterization
                        Genetic and antigenic characterization and antiviral susceptibility of influenza viruses collected in the U.S. are summarized in this report.



                        Illness

                        Outpatient Illness: ILINet
                        Visits to health care providers for influenza-like illness (ILI) decreased from 5.2% last week to 3.9% this week. All regions are above their baselines.



                        Outpatient Illness: ILINet Activity Map

                        The number of jurisdictions experiencing high ILI activity decreased from 31 last week to 21 this week.



                        Geographic Spread

                        The number of jurisdictions reporting regional or widespread influenza activity decreased from 41 last week to 31 this week.




                        Severe Disease



                        Hospitalizations
                        The overall cumulative hospitalization rate for the season increased to 68.2 per 100,000.


                        P&I Mortality
                        The percentage of deaths attributed to pneumonia and influenza is 10.0%, above the epidemic threshold of 7.1%.


                        Pediatric Deaths
                        4 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 166.



                        All data are preliminary and may change as more reports are received.
                        A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.
                        Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

                        Key Points
                        • Nationally, the percent of laboratory specimens testing positive for influenza at clinical laboratories continued to decrease and is now low.
                        • ILI activity continued to decrease nationally but remains elevated.
                        • Recent changes in healthcare seeking behavior, including increasing use of telemedicine and recommendations to limit emergency department (ED) visits to severe illness, as well as increasing levels of social distancing, are affecting the number of persons with ILI and their reasons for seeking care in outpatient and ED settings.
                        • Laboratory confirmed influenza-associated hospitalization rates for the U.S. population overall are higher than most recent seasons and rates for children 0-4 years and adults 18-49 years are the highest CDC has on record for these age groups, surpassing rates reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children (5-17 years) are higher than any recent regular season but remain lower than rates experienced by this age group during the pandemic.
                        • The percent of deaths associated with pneumonia and influenza is above the epidemic threshold. The increase is due to an increase in pneumonia deaths rather than influenza deaths and likely reflects COVID-19 activity.
                        • 166 influenza-associated deaths in children have been reported so far this season. This number is high compared to recent seasons, but remains lower than the 2017-2018 season during which 188 pediatric deaths were reported.
                        • CDC estimates that so far this season there have been at least 39 million flu illnesses, 410,000 hospitalizations and 24,000 deaths from flu.
                        • Antiviral medications are an important adjunct to flu vaccine in the control of influenza. Almost all (>99%) of the influenza viruses tested this season are susceptible to the four FDA-approved influenza antiviral medications recommended for use in the U.S. this season.
                        • With ongoing declines in influenza activity and the continued effects of the COVID-19 pandemic on outpatient ILI and P&I mortality data, this will be the final week of a full FluView report. More detailed interpretation of data from these systems can be found in COVIDView starting next week (week 15).



                        U.S. Virologic Surveillance

                        Clinical Laboratories

                        The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.
                        22,324 1,303,970
                        180 (0.8%) 247,785 (19.0%)
                        105 (58.3%) 132,461 (53.5%)
                        75 (41.7%) 115,324 (46.5%)

                        View Chart Data | View Full Screen
                        Public Health Laboratories

                        The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
                        356 81,392
                        35 43,456
                        31 (88.6%) 24,822 (57.1%)
                        28 (96.6%) 22,324 (92.6%)
                        1 (3.4%) 1,780 (7.4%)
                        2 718
                        4 (11.4%) 18,634 (42.9%)
                        0 (0.0%) 238 (1.6%)
                        0 (0.0%) 14,198 (98.4%)
                        4 4,198
                        While influenza B/Victoria viruses predominated earlier in the season, during recent weeks, influenza A(H1N1)pdm09 viruses have been reported more frequently than B/Victoria viruses nationally and in all surveillance regions. For the season, A(H1N1)pdm09 viruses are the predominant virus nationally. Regional and state level data about circulating influenza viruses can be found on FluView Interactive.
                        The predominant virus also varies by age group. Nationally, for the season overall, influenza B viruses are the most commonly reported influenza viruses among persons 5-24 years, while influenza A viruses are the most commonly reported influenza viruses among persons 0-4 years and 25 years and older. In the most recent three weeks, influenza A viruses are the most commonly reported influenza viruses in all age groups.


                        View Chart Data | View Full Screen

                        Additional virologic surveillance information for current and past seasons:
                        Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data


                        Influenza Virus Characterization

                        CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local health laboratories using Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in circulating influenza viruses. Antigenic characterization data are based on an animal model (influenza-naive ferrets), and do not reflect pre-existing protection provided by past influenza infections and vaccinations. Additional antigenic characterization studies involving people vaccinated with current influenza vaccines are conducted later in the season; these data account for pre-existing protection in different populations against circulating influenza viruses. Genetic and antigenic characterization data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people. Interim estimates of 2019-2020 flu vaccine effectiveness have been released.
                        CDC genetically characterized 2,463 influenza viruses collected in the U.S. from September 29, 2019, to April 4, 2020.
                        896
                        6B.1A 896 (100%)
                        510
                        3C.2a 480 (94.1%) 2a1 480 (94.1%)
                        2a2 0
                        2a3 0
                        2a4 0
                        3C.3a 30 (5.9%) 3a 30 (5.9%)
                        965
                        V1A 965 (100%) V1A 0
                        V1A.1 60 (6.2%)
                        V1A.3 905 (93.8%)
                        92
                        Y3 92 (100%)
                        CDC antigenically characterizes a subset of influenza viruses by hemagglutination inhibition (HI) or neutralization based Focus Reduction assays (FRA). Antigenic drift is evaluated by comparing antigenic properties of cell-propagated reference viruses representing currently recommended vaccine components with those of cell-propagated circulating viruses. CDC antigenically characterized 547 influenza viruses collected in the United States from September 29, 2019, to April 4, 2020. These data are not used to make calculations about vaccine effectiveness (VE). CDC conducts VE studies each year to measure the benefits of flu vaccines in people.
                        Influenza A Viruses
                        • A (H1N1)pdm09: 212 A(H1N1)pdm09 viruses were antigenically characterized by HI with ferret antisera, and 175 (82.5%) were antigenically similar (reacting at titers that were within 4-fold of the homologous virus titer) to cell-propagated A/Brisbane/02/2018-like reference viruses representing the A(H1N1)pdm09 component for the 2019-20 Northern Hemisphere influenza vaccines. The decrease in the percent of A(H1N1)pdm09 viruses similar to A/Brisbane/02/2018 is due to some of the recent viruses selected for testing having a single amino acid change that is antigenically distinguishable in antigenic assays using ferret sera. Similar viruses were observed last season as well and these represented a small proportion of virus circulating. We have observed an increase in the proportion of H1N1pdm09 viruses with this change late in the US season.
                        • A (H3N2): 86 A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 40 (46.5%) were antigenically similar to cell-propagated A/Kansas/14/2017-like reference viruses representing the A(H3N2) component for the 2019-20 Northern Hemisphere influenza vaccines.

                        Influenza B Viruses
                        • B/Victoria: 201 B/Victoria lineage viruses, including viruses from both co-circulating sub-clades, were antigenically characterized by HI with ferret antisera, and 120 (59.7%) were antigenically similar to cell-propagated B/Colorado/06/2017-like reference viruses representing the B/Victoria component for the 2019-20 Northern Hemisphere influenza vaccines.
                        • B/Yamagata: 48 B/Yamagata lineage viruses were antigenically characterized by HI with ferret antisera, and all 48 (100%) were antigenically similar to cell-propagated B/Phuket/3073/2013-like reference viruses representing the B/Yamagata component for the 2019-20 Northern Hemisphere influenza vaccines.


                        CDC also assesses susceptibility of influenza viruses to the antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Viruses collected in the United States since September 29, 2019, were tested for antiviral susceptibility as follows:
                        2,433 885 502 954 92
                        1 (0.04%) (0.0%) (0.0%) 1 (0.1%) (0.0%)
                        4 (0.2%) 4 (0.5%) (0.0%) (0.0%) (0.0%)
                        2,433 885 502 954 92
                        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                        5 (0.2%) 4 (0.5%) (0.0%) 1 (0.1%) (0.0%)
                        2,433 885 502 954 92
                        2 (0.1%) (0.0%) (0.0%) 2 (0.2%) (0.0%)
                        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                        2,541 884 584 978 95
                        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                        *Six influenza viruses showed reduced or highly reduced inhibition by at least one neuraminidase inhibitor. Four A(H1N1)pdm09 viruses showed highly reduced inhibition to oseltamivir and peramivir while showing normal inhibition to zanamivir. In addition, one B/Victoria virus showed highly reduced inhibition to peramivir and reduced inhibition to oseltamivir and zanamivir, while another influenza B/Victoria virus showed reduced inhibition to zanamivir.

                        A total of 556 additional viruses (211 A(H1N1)pdm09, 32 A(H3N2), and 313 B) collected in Alabama, Alaska, Florida, Illinois, Iowa, Louisiana, Massachusetts, Michigan, Nevada, New York, North Carolina, Pennsylvania, South Dakota, Virginia and Wisconsin were analyzed for resistance to neuraminidase inhibitors by pyrosequencing assay. Three (1.4%) of the 211 A(H1N1)pdm09 viruses tested had the H275Y amino acid substitution in the neuraminidase and showed highly reduced inhibition by oseltamivir and peramivir. No molecular markers associated with reduced or highly reduced inhibition by neuraminidase inhibitors were detected in A(H3N2) and type B viruses tested.



                        Outpatient Illness Surveillance

                        ILINet

                        Nationwide during week 14, 3.9% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%.

                        View Chart Data (current season only) | View Full Screen

                        On a regional level, the percentage of outpatient visits for ILI ranged from 2.4% to 10.0% during week 14. All regions decreased in percentage of outpatient visits for ILI compared to last week, but all regions reported a percentage of outpatient visits for ILI above their region-specific baselines.
                        ILI Activity Map

                        Data collected in ILINet are used to produce a measure of ILI activity* by state.
                        During week 14, the following ILI activity levels were experienced:
                        • High – the District of Columbia, New York City, and 19 states (Colorado, Connecticut, Georgia, Idaho, Illinois, Kansas, Louisiana, Maryland, Massachusetts, New Jersey, New York, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Vermont, Virginia, and Wisconsin)
                        • Moderate – four states (Alabama, Mississippi, New Mexico, and Washington)
                        • Low - 12 states (California, Kentucky, Maine, Montana, Nebraska, Nevada, North Carolina, North Dakota, Ohio, Texas, Utah, and West Virginia)
                        • Minimal - Puerto Rico and 15 states (Alaska, Arizona, Arkansas, Delaware, Florida, Hawaii, Indiana, Iowa, Michigan, Minnesota, Missouri, New Hampshire, Rhode Island, South Dakota, and Wyoming)
                        • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                        *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.
                        Among the 21 jurisdictions with high ILI activity, ILI increased relative to the previous week in two, remained stable in two and declined in 17. Sixteen of the jurisdictions with high ILI activity also had clinical laboratory data available and in those, the percent of specimens testing positive for influenza decreased in all but one.

                        Additional information about medically attended visits for ILI for current and past seasons:
                        Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map



                        Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                        The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
                        During week 14, the following influenza activity was reported:
                        • Widespread – 11 states (Alaska, Georgia, Indiana, Louisiana, Maryland, Nevada, North Carolina, Oklahoma, Tennessee, Virginia and Wisconsin)
                        • Regional – Puerto Rico and 19 states (Alabama, Arizona, Colorado, Connecticut, Idaho, Illinois, Kansas, Maine, Massachusetts, Michigan, Mississippi, Montana, New Hampshire, New Jersey, Ohio, South Carolina, Texas, Vermont and Washington)
                        • Local – the District of Columbia and 12 states (Arkansas, Hawaii, Iowa, Missouri, Nebraska, New Mexico, North Dakota, Pennsylvania, South Dakota, Utah, West Virginia and Wyoming)
                        • Sporadic – the U.S. Virgin Islands and seven states (California, Delaware, Florida, Kentucky, Minnesota, New York and Oregon)
                        • No Activity – one state (Rhode Island)
                        • Guam did not report.

                        Additional geographic spread surveillance information for current and past seasons:
                        Surveillance Methods | FluView Interactive



                        Influenza-Associated Hospitalizations

                        The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
                        A total of 19,802 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and April 4, 2020; 14,309 (72.3%) were associated with influenza A virus, 5,379 (27.2%) with influenza B virus, 59 (0.3%) with influenza A virus and influenza B virus co-infection, and 55 (0.3%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 3,806 (94.5%) were A(H1N1)pdm09 virus and 223 (5.5%) were A(H3N2).
                        The overall cumulative hospitalization rate was 68.2 per 100,000 population, which is higher than all recent seasons at this time of year except for the 2017-18 season. Rates in children 0-4 years old and adults 18-49 years old are now the highest CDC has on record for these age groups, surpassing the rate reported during the 2009 H1N1 pandemic. Hospitalization rates for school-aged children are higher than any recent regular season but lower than rates during the pandemic.

                        View Full Screen
                        The highest rate of hospitalization is among adults aged ≥ 65, followed by children aged 0-4 years and adults aged 50-64 years.
                        Overall 68.2
                        0-4 years 94.1
                        5-17 years 24.6
                        18-49 years 35.6
                        50-64 years 90.2
                        65+ years 179.7
                        Among 3,433 hospitalized adults with information on underlying medical conditions, 92.3% had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, obesity, and chronic lung disease. Among 569 hospitalized children with information on underlying medical conditions, 48.5% had at least one underlying medical condition; the most commonly reported was asthma. Among 600 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 27.2% were pregnant.

                        View Full Screen
                        Additional hospitalization surveillance information for current and past seasons and additional age groups:
                        Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics



                        Pneumonia and Influenza (P&I) Mortality Surveillance

                        Based on National Center for Health Statistics (NCHS) mortality surveillance data available on March 26, 2020, 10.0% of the deaths occurring during the week ending March 28, 2020 (week 13) were due to P&I. This percentage is above the epidemic threshold of 7.1% for week 13.

                        View Chart Data | View Full Screen

                        While the percent of all deaths due to P&I has increased during weeks 9-13 (7.4-10.0%), the percent of all deaths with Influenza listed as a cause have decreased (from 1.0% to 0.7%) over this same time period. The increase in pneumonia deaths during this time period are likely associated with COVID-19 rather than influenza.

                        Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                        Surveillance Methods | FluView Interactive



                        Influenza-Associated Pediatric Mortality

                        Four influenza-associated pediatric deaths occurring during the 2019-2020 season between weeks 7 and 14 (the weeks ending February 15, 2020 and April 4, 2020) were reported to CDC during week 14. Two were associated with influenza A viruses, and one was subtyped as an A(H1N1)pdm09 virus. Two were associated with influenza B viruses, and neither had a lineage determined.
                        Of the 166 influenza-associated pediatric deaths occurring during the 2019-2020 season and reported to CDC:
                        • 104 deaths were associated with influenza B viruses, and 25 had a lineage determined; all were B/Victoria viruses.
                        • 62 deaths were associated with influenza A viruses, and 36 were subtyped; 35 were A(H1N1)pdm09 viruses, and one was an A(H3) virus.


                        View Full Screen

                        Additional pediatric mortality surveillance information for current and past seasons:
                        Surveillance Methods | FluView Interactive




                        Additional National and International Influenza Surveillance Information


                        FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
                        National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html
                        U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information

                        World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
                        WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
                        Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
                        Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
                        Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports




                        Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.
                        An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.





                        Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.



                        Twitter: @RonanKelly13
                        The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

                        Comment


                        • #27

                          Weekly U.S. Influenza Surveillance Report


                          Note: The COVID-19 pandemic is affecting healthcare seeking behavior. The number of persons and their reasons for seeking care in the outpatient and ED settings is changing. These changes impact data from ILINet in ways that are difficult to differentiate from changes in illness levels, therefore ILINet data should be interpreted with caution.


                          Key Updates for Week 15, ending April 11, 2020
                          Laboratory confirmed flu activity as reported by clinical laboratories is now low. Influenza-like illness activity, while lower than last week, is still elevated. Influenza severity indicators remain moderate to low overall, but hospitalization rates differ by age group, with high rates among children and young adults.




                          Viruses



                          Clinical Labs
                          The percentage of respiratory specimens testing positive for influenza at clinical laboratories decreased from 0.9% last week to 0.4% this week.


                          Public Health Labs
                          Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.


                          Virus Characterization
                          Reporting of genetic and antigenic characterization and antiviral susceptibility of influenza viruses has been stopped and will resume with the 2020-2021 season.



                          Illness

                          Outpatient Illness: ILINet
                          Visits to health care providers for influenza-like illness (ILI) decreased from 3.9% last week to 2.9% this week. 5 of 10 regions are at or above their baselines.



                          Outpatient Illness: ILINet Activity Map

                          The number of jurisdictions experiencing high or very high ILI activity decreased from 21 last week to 12 this week.



                          Geographic Spread

                          The number of jurisdictions reporting regional or widespread influenza activity decreased from 31 last week to 17 this week.




                          Severe Disease



                          Hospitalizations
                          The overall cumulative hospitalization rate for the season increased to 68.3 per 100,000.


                          P&I Mortality
                          The percentage of deaths attributed to pneumonia and influenza is 11.9%, above the epidemic threshold of 7.0%.


                          Pediatric Deaths
                          2 influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 168.



                          All data are preliminary and may change as more reports are received.
                          A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.
                          Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

                          Key Points
                          • Nationally, influenza activity is now low.
                          • With ongoing declines in influenza activity and the continued effects of the COVID-19 pandemic, FluView will be abbreviated for the remainder of the 2019-2020 season.
                          • More detailed interpretation of data and more COVID-19 specific information can be found in COVIDView.



                          U.S. Virologic Surveillance

                          Clinical Laboratories

                          The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.

                          View Chart Data | View Full Screen
                          Public Health Laboratories

                          The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.

                          View Chart Data | View Full Screen

                          Additional virologic surveillance information for current and past seasons:
                          Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data



                          Outpatient Illness Surveillance

                          ILINet

                          Nationwide during week 15, 2.9% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is above the national baseline of 2.4%.

                          View Chart Data (current season only) | View Full Screen

                          On a regional level, the percentage of outpatient visits for ILI ranged from 1.3% to 8.3% during week 15. The percent of outpatient visits for ILI decreased in all regions compared to last week. Regions 1, 2, 3, 5, and 10 reported a percentage of outpatient visits for ILI at or above their region-specific baselines. All other regions are below their region-specific baselines.
                          ILI Activity Map

                          Data collected in ILINet are used to produce a measure of ILI activity* by state.
                          During week 15, the following ILI activity levels were experienced:
                          • Very High – New York City and 1 state (New Jersey)
                          • High – the District of Columbia, Puerto Rico, and 8 states (Connecticut, Georgia, Louisiana, Maryland, Massachusetts, New York, South Carolina, and Wisconsin)
                          • Moderate – six states (Illinois, Oklahoma, Oregon, Pennsylvania, Vermont, and Virginia)
                          • Low - 11 states (Alabama, Alaska, Colorado, Idaho, Kansas, Minnesota, Nebraska, New Mexico, Tennessee, Texas, and Washington)
                          • Minimal - 24 states (Arizona, Arkansas, California, Delaware, Florida, Hawaii, Indiana, Iowa, Kentucky, Maine, Michigan, Mississippi, Missouri, Montana, Nevada, New Hampshire, North Carolina, North Dakota, Ohio, Rhode Island, South Dakota, Utah, West Virginia, and Wyoming)
                          • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                          *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

                          Additional information about medically attended visits for ILI for current and past seasons:
                          Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map



                          Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                          The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
                          During week 15, the following influenza activity was reported:
                          • Widespread – 3 states (Indiana, Louisiana, and Maryland)
                          • Regional – Puerto Rico and 13 states (Arizona, Georgia, Idaho, Maine, Nevada, New Hampshire, New Jersey, North Carolina, Ohio, Oklahoma, South Carolina, Tennessee and Wisconsin)
                          • Local – the District of Columbia and 11 states (Colorado, Illinois, Kansas, Massachusetts, Michigan, Montana, Oregon, Pennsylvania, Texas, Washington and Wyoming)
                          • Sporadic – the U.S. Virgin Islands and 19 states (Alabama, Alaska, Arkansas, California, Connecticut, Florida, Hawaii, Iowa, Kentucky, Minnesota, Mississippi, Missouri, Nebraska, New York, North Dakota, South Dakota, Utah, Vermont and West Virginia)
                          • No Activity – four states (Delaware, New Mexico, Rhode Island and Virginia)
                          • Guam did not report.

                          Additional geographic spread surveillance information for current and past seasons:
                          Surveillance Methods | FluView Interactive



                          Influenza-Associated Hospitalizations

                          The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
                          A total of 19,845 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and April 11, 2020 with a cumulative hospitalization rate of 68.3 per 100,000 population.

                          View Full Screen

                          View Full Screen
                          Additional hospitalization surveillance information for current and past seasons and additional age groups:
                          Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics



                          Pneumonia and Influenza (P&I) Mortality Surveillance

                          Based on National Center for Health Statistics (NCHS) mortality surveillance data available on April 16, 2020, 11.9% of the deaths occurring during the week ending April 11, 2020 (week 15) were due to P&I. This percentage is above the epidemic threshold of 7.0% for week 15.

                          View Chart Data | View Full Screen

                          Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                          Surveillance Methods | FluView Interactive



                          Influenza-Associated Pediatric Mortality

                          Two influenza-associated pediatric deaths occurring during the 2019-2020 season were reported to CDC during week 15. One death was associated with an influenza A (H1N1)pdm09 virus and occurred during week 52 (the week ending December 28, 2019). One death was associated with an influenza B/Victoria virus and occurred during week 2 (the week ending January 11, 2020).
                          A total of 168 influenza-associated pediatric deaths occurring during the 2019-2020 season have been reported to CDC.



                          View Full Screen

                          Additional pediatric mortality surveillance information for current and past seasons:
                          Surveillance Methods | FluView Interactive




                          Additional National and International Influenza Surveillance Information


                          FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
                          National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html
                          U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information

                          World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
                          WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
                          Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
                          Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
                          Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports




                          Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.
                          An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.
                          --------------------------------------------------------------------------------

















                          Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.
                          Twitter: @RonanKelly13
                          The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

                          Comment


                          • #28

                            Weekly U.S. Influenza Surveillance Report


                            Note: The COVID-19 pandemic is affecting healthcare seeking behavior. The number of persons and their reasons for seeking care in the outpatient and ED settings is changing. These changes impact data from ILINet in ways that are difficult to differentiate from changes in illness levels, therefore ILINet data should be interpreted with caution. CDC is tracking the COVID-19 pandemic in a weekly publication called COVIDView.


                            Key Updates for Week 16, ending April 18, 2020
                            Laboratory confirmed flu activity as reported by clinical laboratories is now low. Influenza-like illness activity continues to decrease and is below the national baseline. The percent of deaths due to pneumonia or influenza (P&I) is high but the increase is due primarily to COVID-19, not influenza. Reported pediatric flu deaths for the season are high at 169.




                            Viruses



                            Clinical Labs
                            The percentage of respiratory specimens testing positive for influenza at clinical laboratories is 0.4%. This is approximately the same as the previous week.


                            Public Health Labs
                            Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.


                            Virus Characterization
                            Reporting of genetic and antigenic characterization and antiviral susceptibility of influenza viruses has been stopped and will resume with the 2020-2021 season.



                            Illness

                            Outpatient Illness: ILINet
                            Visits to health care providers for influenza-like illness (ILI) decreased from 2.8% last week to 2.2% this week. Nationally, ILI is below baseline, but 4 of 10 regions are above their baselines.



                            Outpatient Illness: ILINet Activity Map

                            The number of jurisdictions experiencing high or very high ILI activity decreased from 12 last week to 8 this week.



                            Geographic Spread

                            The number of jurisdictions reporting regional or widespread influenza activity decreased from 17 last week to 10 this week.




                            Severe Disease



                            Hospitalizations
                            The overall cumulative hospitalization rate for the season increased to 68.6 per 100,000.


                            P&I Mortality
                            The percentage of deaths attributed to pneumonia and influenza is 11.4%, down from 14.5% last week, but above the epidemic threshold of 6.9%.


                            Pediatric Deaths
                            One influenza-associated pediatric death occurring during the 2019-2020 season was reported this week. The total for the season is 169.



                            All data are preliminary and may change as more reports are received.
                            A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.
                            Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

                            Key Points
                            • Nationally, influenza activity is now low.
                            • With ongoing declines in influenza activity and the continued effects of the COVID-19 pandemic, FluView will be abbreviated for the remainder of the 2019-2020 season.
                            • More detailed interpretation of data and more COVID-19 specific information can be found in COVIDView.



                            U.S. Virologic Surveillance

                            Clinical Laboratories

                            The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.

                            View Chart Data | View Full Screen
                            Public Health Laboratories

                            The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.

                            View Chart Data | View Full Screen

                            Additional virologic surveillance information for current and past seasons:
                            Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data



                            Outpatient Illness Surveillance

                            ILINet

                            Nationwide during week 16, 2.2% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is below the national baseline of 2.4%.

                            View Chart Data (current season only) | View Full Screen

                            On a regional level, the percentage of outpatient visits for ILI ranged from 1.1% to 5.4% during week 16. The percent of outpatient visits for ILI decreased in all regions compared to last week. Regions 1, 2, 3, and 10 reported a percentage of outpatient visits for ILI above their region-specific baselines. All other regions are below their region-specific baselines.
                            ILI Activity Map

                            Data collected in ILINet are used to produce a measure of ILI activity* by state.
                            During week 16, the following ILI activity levels were experienced:
                            • Very High – one state (New Jersey)
                            • High – the District of Columbia, New York City, and five states (Connecticut, Louisiana, Maryland, Massachusetts, and New York)
                            • Moderate – Puerto Rico and two states (Idaho and Wisconsin)
                            • Low - eight states (Georgia, Illinois, New Mexico, Oklahoma, Pennsylvania, South Carolina, Vermont, and Virginia)
                            • Minimal - 34 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Delaware, Florida, Hawaii, Indiana, Iowa, Kansas, Kentucky, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, North Carolina, North Dakota, Ohio, Oregon, Rhode Island, South Dakota, Tennessee, Texas, Utah, Washington, West Virginia, and Wyoming)
                            • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                            *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

                            Additional information about medically attended visits for ILI for current and past seasons:
                            Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map



                            Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                            The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
                            During week 16, the following influenza activity was reported:
                            • Regional – Puerto Rico and 9 states (Georgia, Idaho, Indiana, Louisiana, Maryland, Nevada, South Carolina, Tennessee and Wisconsin)
                            • Local – 12 states (Alabama, Arizona, Maine, Massachusetts, Montana, New Hampshire, New Jersey, North Carolina, Ohio, Oklahoma, Pennsylvania and Virginia)
                            • Sporadic – the District of Columbia, the U.S. Virgin Islands and 26 states (Alaska, Arkansas, California, Colorado, Connecticut, Florida, Hawaii, Illinois, Iowa, Kansas, Kentucky, Michigan, Minnesota, Mississippi, Missouri, Nebraska, New York, North Dakota, Oregon, South Dakota, Texas, Utah, Vermont, Washington, West Virginia and Wyoming)
                            • No Activity – three states (Delaware, New Mexico and Rhode Island)
                            • Guam did not report.

                            Additional geographic spread surveillance information for current and past seasons:
                            Surveillance Methods | FluView Interactive



                            Influenza-Associated Hospitalizations

                            The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
                            A total of 19,932 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and April 18, 2020 with a cumulative hospitalization rate of 68.6 per 100,000 population.

                            View Full Screen

                            View Full Screen
                            Additional hospitalization surveillance information for current and past seasons and additional age groups:
                            Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics



                            Pneumonia and Influenza (P&I) Mortality Surveillance

                            Based on National Center for Health Statistics (NCHS) mortality surveillance data available on April 23, 2020, 11.4% of the deaths occurring during the week ending April 18, 2020 (week 16) were due to P&I. This percentage is above the epidemic threshold of 6.9% for week 16.

                            View Chart Data | View Full Screen

                            Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                            Surveillance Methods | FluView Interactive



                            Influenza-Associated Pediatric Mortality

                            One influenza-associated pediatric death occurring during the 2019-2020 season was reported to CDC during week 16. It was associated with an influenza B virus with no lineage determined and occurred during week 5 (the week ending February 1, 2020).
                            A total of 169 influenza-associated pediatric deaths occurring during the 2019-2020 season have been reported to CDC.



                            View Full Screen

                            Additional pediatric mortality surveillance information for current and past seasons:
                            Surveillance Methods | FluView Interactive




                            Additional National and International Influenza Surveillance Information


                            FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
                            National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html
                            U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information

                            World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
                            WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
                            Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
                            Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
                            Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports




                            Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.
                            An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.
                            --------------------------------------------------------------------------------

















                            Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.
                            Twitter: @RonanKelly13
                            The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

                            Comment


                            • #29

                              Weekly U.S. Influenza Surveillance Report


                              Note: The COVID-19 pandemic is affecting healthcare seeking behavior. The number of persons and their reasons for seeking care in the outpatient and ED settings is changing. These changes impact data from ILINet in ways that are difficult to differentiate from changes in illness levels, therefore ILINet data should be interpreted with caution. CDC is tracking the COVID-19 pandemic in a weekly publication called COVIDView.


                              Key Updates for Week 18, ending May 2, 2020
                              Laboratory confirmed flu activity as reported by clinical laboratories remains low. Influenza-like illness activity continues to decrease and is below the national baseline. The percent of deaths due to pneumonia or influenza (P&I) is decreasing but remains elevated, primarily due to COVID-19, not influenza. Reported pediatric flu deaths for the season are high at 174.




                              Viruses



                              Clinical Labs
                              The percentage of respiratory specimens testing positive for influenza at clinical laboratories is 0.3%. This is similar to the previous week (0.2%).


                              Public Health Labs
                              Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.


                              Virus Characterization
                              Reporting of genetic and antigenic characterization and antiviral susceptibility of influenza viruses has been stopped and will resume with the 2020-2021 season.



                              Illness

                              Outpatient Illness: ILINet
                              Visits to health care providers for influenza-like illness (ILI) decreased from 1.8% last week to 1.5% this week. ILI is below baseline nationally and for all regions.



                              Outpatient Illness: ILINet Activity Map

                              One jurisdiction experienced high ILI activity this week compared to three jurisdictions that experienced high activity last week.



                              Geographic Spread

                              No jurisdictions reported regional or widespread influenza activity this week.




                              Severe Disease



                              Hospitalizations
                              The overall cumulative hospitalization rate for the season increased to 69.2 per 100,000.


                              P&I Mortality
                              The percentage of deaths attributed to pneumonia and influenza is 7.4%, down from 12.3% last week, but above the epidemic threshold of 6.7%.


                              Pediatric Deaths
                              Four influenza-associated pediatric deaths occurring during the 2019-2020 season were reported this week. The total for the season is 174.



                              All data are preliminary and may change as more reports are received.
                              A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.
                              Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.

                              Key Points
                              • Nationally, influenza activity remains low.
                              • CDC will continue to track influenza activity year-round as always, but as flu activity remains low, an abbreviated FluView will be published weekly during the remainder of the 2019-2020 season.
                              • More detailed interpretation of data and more COVID-19 specific information can be found in COVIDView



                              U.S. Virologic Surveillance

                              Clinical Laboratories

                              The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.

                              View Chart Data | View Full Screen
                              Public Health Laboratories

                              The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.

                              View Chart Data | View Full Screen

                              Additional virologic surveillance information for current and past seasons:
                              Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data



                              Outpatient Illness Surveillance

                              ILINet

                              Nationwide during week 18, 1.5% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is below the national baseline of 2.4%.

                              View Chart Data (current season only) | View Full Screen

                              On a regional level, the percentage of outpatient visits for ILI ranged from 0.9% to 2.8% during week 18. Compared to last week, the percent of outpatient visits for ILI increased slightly in region 7, but decreased in all other regions. All regions reported a percentage of outpatient visits for ILI below their region-specific baselines.
                              ILI Activity Map

                              Data collected in ILINet are used to produce a measure of ILI activity* by state.
                              During week 18, the following ILI activity levels were experienced:
                              • High – one state (Maryland)
                              • Moderate – Puerto Rico and two states (New Jersey and Wisconsin)
                              • Low – three states (Massachusetts, Minnesota, and Vermont)
                              • Minimal - the District of Columbia, New York City, and 44 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Michigan, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, and Wyoming)
                              • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                              *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

                              Additional information about medically attended visits for ILI for current and past seasons:
                              Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map



                              Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                              The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
                              During week 18, the following influenza activity was reported:
                              • Local – Puerto Rico and seven states (Arizona, Indiana, Louisiana, Maryland, North Carolina, Oklahoma and Wisconsin)
                              • Sporadic – the District of Columbia, the U.S. Virgin Islands and 33 states (Alabama, Alaska, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Idaho, Illinois, Iowa, Maine, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New York, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Washington, West Virginia, and Wyoming)
                              • No Activity – 10 states (Delaware, Kansas, Kentucky, Mississippi, New Hampshire, New Mexico, Oregon, Rhode Island, Vermont and Virginia)
                              • Guam did not report.

                              Additional geographic spread surveillance information for current and past seasons:
                              Surveillance Methods | FluView Interactive



                              Influenza-Associated Hospitalizations

                              The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
                              As in previous seasons, patients admitted for laboratory-confirmed influenza-related hospitalization after April 30, 2020 will not be included in FluSurv-NET. Data on patients admitted through April 30, 2020 will continue to be updated as additional information is received.
                              A total of 20,094 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and May 2, 2020 with a cumulative hospitalization rate of 69.2 per 100,000 population.

                              View Full Screen

                              View Full Screen
                              Additional hospitalization surveillance information for current and past seasons and additional age groups:
                              Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics



                              Pneumonia and Influenza (P&I) Mortality Surveillance

                              Based on National Center for Health Statistics (NCHS) mortality surveillance data available on May 7, 2020, 7.4% of the deaths occurring during the week ending May 2, 2020 (week 18) were due to P&I. This percentage is above the epidemic threshold of 6.7% for week 18.

                              View Chart Data | View Full Screen

                              Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                              Surveillance Methods | FluView Interactive



                              Influenza-Associated Pediatric Mortality

                              Four influenza-associated pediatric deaths occurring during the 2019-2020 season were reported to CDC during week 18. Three were associated with an influenza A (H1N1)pdm09 virus and occurred during weeks 3 (the week ending January 18, 2020) and 11 (the week ending March 14, 2020). One was associated with an influenza B virus with no lineage determined and occurred during week 17 (the week ending April 25, 2020).
                              A total of 174 influenza-associated pediatric deaths occurring during the 2019-2020 season have been reported to CDC.


                              View Full Screen

                              Additional pediatric mortality surveillance information for current and past seasons:
                              Surveillance Methods | FluView Interactive




                              Additional National and International Influenza Surveillance Information


                              FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
                              National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html
                              U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information

                              World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
                              WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
                              Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
                              Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
                              Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports




                              Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.
                              An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.
                              --------------------------------------------------------------------------------

















                              Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.
                              Twitter: @RonanKelly13
                              The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

                              Comment


                              • #30

                                Weekly U.S. Influenza Surveillance Report


                                Note: The COVID-19 pandemic is affecting healthcare seeking behavior. The number of persons and their reasons for seeking care in the outpatient and ED settings is changing. These changes impact data from ILINet in ways that are difficult to differentiate from changes in illness levels, therefore ILINet data should be interpreted with caution. CDC is tracking the COVID-19 pandemic in a weekly publication called COVIDView.


                                Key Updates for Week 19, ending May 9, 2020
                                Laboratory confirmed flu activity as reported by clinical laboratories remains low. Influenza-like illness activity continues to decrease and is below the national baseline. The percent of deaths due to pneumonia or influenza (P&I) is decreasing but remains elevated, primarily due to COVID-19, not influenza. Reported pediatric flu deaths for the season are high at 174.




                                Viruses



                                Clinical Labs
                                The percentage of respiratory specimens testing positive for influenza at clinical laboratories is 0.3%. This is similar to the previous week (0.2%).


                                Public Health Labs
                                Nationally, influenza A(H1N1)pdm09 viruses are now the most commonly reported influenza viruses this season.


                                Virus Characterization
                                Reporting of genetic and antigenic characterization and antiviral susceptibility of influenza viruses will resume with the 2020-2021 season.



                                Illness

                                Outpatient Illness: ILINet
                                Visits to health care providers for influenza-like illness (ILI) decreased from 1.5% last week to 1.2% this week. ILI is below baseline nationally and for all regions.



                                Outpatient Illness: ILINet Activity Map

                                Similar to last week, one jurisdiction experienced high ILI activity this week.


                                Geographic Spread

                                No jurisdictions reported regional or widespread influenza activity this week.



                                Severe Disease



                                Hospitalizations
                                The overall cumulative hospitalization rate for the season increased to 69.3 per 100,000.


                                P&I Mortality
                                The percentage of deaths attributed to pneumonia and influenza is 8.1%, down from 10.5% last week, but above the epidemic threshold of 6.6%.


                                Pediatric Deaths
                                There were no influenza-associated pediatric deaths occurring during the 2019-2020 season reported this week. The total for the season is 174.



                                All data are preliminary and may change as more reports are received.
                                A description of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component is available on the surveillance methods page.
                                Additional information on the current and previous influenza seasons for each surveillance component are available on FluView Interactive.
                                Key Points
                                • Nationally, influenza activity remains low.
                                • CDC will continue to track influenza activity year-round as always, but as flu activity remains low, an abbreviated FluView will be published weekly during the remainder of the 2019-2020 season.
                                • More detailed interpretation of data and more COVID-19 specific information can be found in COVIDView



                                U.S. Virologic Surveillance

                                Clinical Laboratories

                                The results of tests performed by clinical laboratories nationwide are summarized below. Data from clinical laboratories (the percentage of specimens tested that are positive for influenza) are used to monitor whether influenza activity is increasing or decreasing.

                                View Chart Data | View Full ScreenPublic Health Laboratories

                                The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.

                                View Chart Data | View Full Screen
                                Additional virologic surveillance information for current and past seasons:
                                Surveillance Methods | FluView Interactive: National, Regional, and State Data or Age Data


                                Outpatient Illness Surveillance

                                ILINet

                                Nationwide during week 19, 1.2% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is below the national baseline of 2.4%.

                                View Chart Data (current season only) | View Full Screen
                                On a regional level, the percentage of outpatient visits for ILI ranged from 0.6% to 2.0% during week 19. Compared to last week, the percent of outpatient visits for ILI stayed the same in region 9, and decreased in all other regions. All regions reported a percentage of outpatient visits for ILI below their region-specific baselines.
                                ILI Activity Map

                                Data collected in ILINet are used to produce a measure of ILI activity* by state.
                                During week 19, the following ILI activity levels were experienced:
                                • High – one state (Wisconsin)
                                • Moderate – Puerto Rico and one state (Maryland)
                                • Low – two states (Idaho and Massachusetts)
                                • Minimal - the District of Columbia, New York City, and 46 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Georgia, Hawaii, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Maine, Michigan, Minnesota, Mississippi, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, and Wyoming)
                                • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.

                                *Data collected in ILINet may disproportionally represent certain populations within a state, and therefore, may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

                                Additional information about medically attended visits for ILI for current and past seasons:
                                Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map


                                Geographic Spread of Influenza as Assessed by State and Territorial Epidemiologists

                                The influenza activity reported by state and territorial epidemiologists indicates geographic spread of influenza viruses but does not measure the severity of influenza activity.
                                During week 19, the following influenza activity was reported:
                                • Local – Puerto Rico and two states (Louisiana and Maryland)
                                • Sporadic – the District of Columbia, the U.S. Virgin Islands and 34 states (Alabama, Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Florida, Georgia, Hawaii, Idaho, Illinois, Indiana, Iowa, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Jersey, New York, North Dakota, Ohio, Pennsylvania, South Carolina, South Dakota, Tennessee, Texas, Utah, Washington, West Virginia, and Wyoming)
                                • No Activity – 14 states (Delaware, Kansas, Kentucky, Maine, Nevada, New Hampshire, New Mexico, North Carolina, Oregon, Rhode Island, South Carolina, Tennessee, Vermont and Virginia)
                                • Guam did not report.

                                Additional geographic spread surveillance information for current and past seasons:
                                Surveillance Methods | FluView Interactive


                                Influenza-Associated Hospitalizations

                                The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in the Emerging Infections Program (EIP) states and Influenza Hospitalization Surveillance Project (IHSP) states.
                                As in previous seasons, patients admitted for laboratory-confirmed influenza-related hospitalization after April 30, 2020 will not be included in FluSurv-NET. Data on patients admitted through April 30, 2020 will continue to be updated as additional information is received.
                                A total of 20,130 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2019 and May 2, 2020 with a cumulative hospitalization rate of 69.3 per 100,000 population.

                                View Full Screen

                                View Full Screen
                                Additional hospitalization surveillance information for current and past seasons and additional age groups:
                                Surveillance Methods | FluView Interactive: Rates by Age or Patient Characteristics


                                Pneumonia and Influenza (P&I) Mortality Surveillance

                                Based on National Center for Health Statistics (NCHS) mortality surveillance data available on May 14, 2020, 8.1% of the deaths occurring during the week ending May 9, 2020 (week 19) were due to P&I. This percentage is above the epidemic threshold of 6.6% for week 19.
                                Weekly mortality surveillance data include a combination of machine coded and manually coded causes of death collected from death certificates. Percentages of deaths due to pneumonia and influenza (P&I) are higher among manually coded records than more rapidly available machine coded records. Due to the additional time needed for manual coding, the initially reported P&I percentages may increase as more data are received and processed.

                                View Chart Data | View Full Screen
                                Additional pneumonia and influenza mortality surveillance information for current and past seasons:
                                Surveillance Methods | FluView Interactive


                                Influenza-Associated Pediatric Mortality

                                No influenza-associated pediatric deaths were reported to CDC during week 19. A total of 174 influenza-associated pediatric deaths occurring during the 2019-2020 season have been reported to CDC.

                                View Full Screen
                                Additional pediatric mortality surveillance information for current and past seasons:
                                Surveillance Methods | FluView Interactive



                                Additional National and International Influenza Surveillance Information


                                FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics. To access these tools, visit http://www.cdc.gov/flu/weekly/fluviewinteractive.htm
                                National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH at https://www.cdc.gov/niosh/topics/absences/default.html
                                U.S. State and local influenza surveillance:Select a jurisdiction below to access the latest local influenza information
                                World Health Organization: Additional influenza surveillance information from participating WHO member nations is available through FluNet and the Global Epidemiology Reports.
                                WHO Collaborating Centers for Influenza located in Australia, China, Japan, the United Kingdom, and the United States (CDC in Atlanta, Georgia).
                                Europe: For the most recent influenza surveillance information from Europe, please see WHO/Europe and the European Centre for Disease Prevention and Control at http://www.flunewseurope.org/.
                                Public Health Agency of Canada: The most up-to-date influenza information from Canada is available at http://www.phac-aspc.gc.ca/fluwatch/
                                Public Health England: The most up-to-date influenza information from the United Kingdom is available at https://www.gov.uk/government/statistics/weekly-national-flu-reports




                                Any links provided to non-Federal organizations are provided solely as a service to our users. These links do not constitute an endorsement of these organizations or their programs by CDC or the Federal Government, and none should be inferred. CDC is not responsible for the content of the individual organization web pages found at these links.
                                An overview of the CDC influenza surveillance system, including methodology and detailed descriptions of each data component, is available at: http://www.cdc.gov/flu/weekly/overview.htm.
                                --------------------------------------------------------------------------------


















                                Seasonal Influenza (Flu)What CDC Does

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                                Learn more about the weekly influenza surveillance report (FluView) prepared by the Influenza Division.
                                Twitter: @RonanKelly13
                                The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

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