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  • #16
    2018-2019 Influenza Season Week 5 ending February 2, 2019

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

    Influenza activity increased in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending February 2, 2019
    • Viral Surveillance:The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories increased. Influenza A viruses have predominated in the United States since the beginning of October. Influenza A(H1N1)pdm09 viruses have predominated in most areas of the country, however influenza A(H3) viruses have predominated in the southeastern United States (HHS Region 4).
      • Virus Characterization:The majority of influenza viruses characterized antigenically and genetically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
      • Antiviral Resistance:The vast majority of influenza viruses tested (>99%) show susceptibility to oseltamivir and peramivir. All influenza viruses tested showed susceptibility to zanamivir.
    • Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) increased to 4.3%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
      • ILI State Activity Indictor Map: New York City and 24 states experienced high ILI activity; Puerto Rico and 10 states experienced moderate ILI activity; the District of Columbia and 13 states experienced low ILI activity; and three states experienced minimal ILI activity.
    • Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 47 states was reported as widespread; two states reported regional activity; the District of Columbia and one state reported local activity; the U.S. Virgin Islands reported sporadic activity; and Guam did not report.
    • Influenza-associated Hospitalizations A cumulative rate of 20.1 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (53.0 hospitalizations per 100,000 population).
    • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
    • Influenza-associated Pediatric Deaths: Four influenza-associated pediatric deaths were reported to CDC during week 5.
    National and Regional Summary of Select Surveillance Components

    Elevated 50 of 54 21.6% Influenza A(H1N1)pdm09
    Elevated 6 of 6 24.8% Influenza A(H1N1)pdm09
    Elevated 3 of 4 19.0% Influenza A(H1N1)pdm09
    Elevated 5 of 6 14.6% Influenza A(H1N1)pdm09
    Elevated 8 of 8 14.4% Influenza A(H3)
    Elevated 6 of 6 16.6% Influenza A(H1N1)pdm09
    Elevated 5 of 5 25.5% Influenza A(H1N1)pdm09
    Elevated 4 of 4 16.5% Approximately equal Influenza A(H1N1)pdm09 and Influenza A(H3)
    Elevated 6 of 6 22.5% Influenza A(H1N1)pdm09
    Elevated 3 of 5 13.7% Influenza A(H1N1)pdm09
    Elevated 4 of 4 19.3% Influenza A(H1N1)pdm09
    *https://www.hhs.gov/about/agencies/i...ces/index.html
    † Elevated means the % of visits for ILI is at or above the national or region-specific baseline
    § Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands
    ‡ National data are for current week; regional data are for the most recent three weeks


    U.S. Virologic Surveillance:

    WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, Guam, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza by virus type. In addition, public health laboratories also report the influenza A subtype (H1 or H3) and influenza B lineage information of the viruses they test and the age or age group of the persons from whom the specimens were collected.
    Additional virologic data, including national, regional and select state-level data, can be found at: http://gis.cdc.gov/grasp/fluview/flu...dashboard.html. Age group proportions and totals by influenza subtype reported by public health laboratories can be found at: http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.
    The results of tests performed by clinical laboratories are summarized below.
    33,362 536,301
    7,205 (21.6%) 54,381 (10.1%)
    7,080 (98.3%) 52,028 (95.7%)
    125 (1.7%) 2,353 (4.3%)

    View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
    The results of tests performed by public health laboratories are summarized below.
    1,442 30,344
    843 12,200
    829 (98.3%) 11,863 (97.2%)
    524 (65.0%) 9,023 (80.0%)
    282 (35.0%) 2,261 (20.0%)
    23 579
    14 (1.7%) 337 (2.8%)
    2 (28.6%) 143 (57.4%)
    5 (71.4%) 106 (42.6%)
    7 88
    *The percent of specimens testing positive for influenza is not reported because public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory and therefore percent positive would not be a valid indicator of influenza activity. Additional information is available at http://www.cdc.gov/flu/weekly/overview.htm.


    View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
    Influenza Virus Characterization:

    Close monitoring of influenza viruses is required to better assess the potential impact on public health. CDC characterizes influenza viruses through one or more tests including genomic sequencing, hemagglutination inhibition (HI) and/or neutralization assays based Focus Reduction assays (FRA). These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. Antigenic and genetic characterization of circulating influenza viruses gives an indication of the influenza vaccine's ability to induce an immune response against the wide array of influenza viruses that are co-circulating every season. However, annual vaccine effectiveness estimates are needed to determine how much protection was provided to the population by vaccination.
    For nearly all influenza-positive surveillance samples received at CDC, next-generation sequencing is performed to determine the genetic identity of circulating influenza viruses and to monitor the evolutionary trajectory of viruses circulating in our population. Virus gene segments are classified into genetic clades/subclades based on phylogenetic analysis. However, genetic changes that classify the clades/subclades do not always result in antigenic changes. “Antigenic drift” is a term used to describe gradual antigenic change that occurs as viruses evolve changes to escape host immune pressure. 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 has antigenically or genetically characterized 769 influenza viruses collected September 30, 2018 – February 2, 2019, and submitted by U.S. laboratories, including 450 influenza A(H1N1)pdm09 viruses, 239 influenza A(H3N2) viruses, and 80 influenza B viruses.
    Influenza A Viruses
    Influenza B Viruses

    The majority of U.S. viruses submitted for characterization come from state and local public health laboratories. Due to Right Size Roadmapconsiderations, specimen submission guidance to laboratories is that, if available, 2 influenza A(H1N1)pdm09, 2 influenza A(H3N2), and 2 influenza B viruses be submitted every other week. Therefore, the numbers of each virus type/subtype characterized should be more balanced across subtypes/lineages but will not reflect the actual proportion of circulating viruses. In the figure below, the results of tests performed by public health labs are shown on the left and CDC sequence results (by genetic clade/subclade) are shown on the right.

    View Chart Data | View Full Screen | View PowerPoint Presentation
      • A (H1N1)pdm09: Phylogenetic analysis of the HA genes from 450 A(H1N1)pdm09 viruses showed that all belonged to clade 6B.1. One hundred ninety-four A(H1N1)pdm09 viruses were antigenically characterized, and 191 (98.5%) were antigenically similar (analyzed using HI with ferret antisera) to A/Michigan/45/2015 (6B.1), a cell-propagated A/Michigan/45/2015-like reference virus representing the A(H1N1)pdm09 component for the 2018-19 Northern Hemisphere influenza vaccines.
      • A (H3N2): Phylogenetic analysis of the HA genes from 239 A(H3N2) viruses revealed extensive genetic diversity with multiple clades/subclades co-circulating. The HA genes of circulating viruses belonged to clade 3C.2a (n=55), subclade 3C.2a1 (n=98) or clade 3C.3a (n=86). One hundred forty-five A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 102 (70.3%) A(H3N2) viruses tested were well-inhibited (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera raised against A/Singapore/INFIMH-16-0019/2016 (3C.2a1), a cell-propagated reference virus representing the A(H3N2) component of 2018-19 Northern Hemisphere influenza vaccines. Forty-three viruses (29.7%) reacted poorly (at titers that were 8-fold or greater reduced compared with that of the homologous virus A/Singapore/INFIMH-16-0019/2016) and of those, 42 (97.7%) belonged to clade 3C.3a.
      • B/Victoria: Phylogenetic analysis of 30 B/Victoria-lineage viruses indicate that all HA genes belonged to genetic clade V1A, however genetic subclades which are antigenically distinct have emerged. Genetic subclades which are antigenically distinct include viruses with a two amino acid deletion (162-163) in the HA protein (V1A.1, previously abbreviated as V1A-2Del) and viruses with a three amino acid deletion (162-164) in the HA protein (abbreviated as V1A-3Del). Twenty-one B/Victoria lineage viruses were antigenically characterized and 15 (71.4%) were antigenically similar with ferret antisera raised against cell-propagated B/Colorado/06/2017-like V1A.1 reference virus. Six (28.6%) reacted poorly (at titers that were 8-fold or greater reduced compared with the homologous virus titer) and belonged to clade V1A.
      • B/Yamagata: Phylogenetic analysis of 50 influenza B/Yamagata-lineage viruses indicate that the HA genes belonged to clade Y3. A total of 33 influenza B/Yamagata-lineage viruses were antigenically characterized, and all were antigenically similar to cell-propagated B/Phuket/3073/2013 (Y3), the reference vaccine virus representing the influenza B/Yamagata-lineage component of the 2018-19 Northern Hemisphere quadrivalent vaccines.
      Antiviral Resistance:

      Testing of influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses for resistance to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using next-generation sequencing analysis and/or a functional assay. Neuraminidase sequences of viruses are inspected to detect the presence of amino acid substitutions,previously associated with reduced or highly reduced inhibition by any of three neuraminidase inhibitors.In addition, a subset of viruses are tested using the neuraminidase inhibition assay with three neuraminidase inhibitors. The level of neuraminidase activity inhibition is reported using the thresholds recommended by the World Health Organization Expert Working Group of the Global Influenza Surveillance and Response System (GISRS)These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with an antiviral-resistant virus.
      Reporting of baloxavir susceptibility testing for the 2018-2019 influenza season will begin later this season. More information regarding influenza antiviral drug resistance can be found here.
      High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.
      Assessment of Virus Susceptibility to Neuraminidase Inhibitors Using Next-Generation Sequencing Analysis and/or Neuraminidase Inhibition Assay

      Oseltamivir Peramivir Zanamivir
      823 2 (0.2%) 2 (0.2%) 823 0 (0%) 2 (0.2%) 823 0 (0%) 0 (0%)
      481 2 (0.4%) 2 (0.4%) 481 0 (0%) 2 (0.4%) 481 0 (0%) 0 (0%)
      254 0 (0%) 0 (0%) 254 0 (0%) 0 (0%) 254 0 (0%) 0 (0%)
      34 0 (0%) 0 (0%) 34 0 (0%) 0 (0%) 34 0 (0%) 0 (0%)
      54 0 (0%) 0 (0%) 54 0 (0%) 0 (0%) 54 0 (0%) 0 (0%)
      Antiviral treatment as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at:http://www.cdc.gov/flu/antivirals/index.htm.



      Outpatient Illness Surveillance:

      Nationwide during week 5, 4.3% 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 2.2%.(ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
      On a regional level, the percentage of outpatient visits for ILI ranged from 2.5% to 7.6% during week 5. All 10 regions reported a percentage of outpatient visits for ILI at or above their region-specific baseline.
      Additional data on medically attended visits for ILI for current and past seasons and by geography (national, HHS region, or select states) are available on FluView Interactive http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

      View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation



      ILINet State Activity Indicator Map:

      Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below, or only slightly above, the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.
      The ILI Activity Indicator Map displays state-specific activity levels for multiple seasons and allows a visual representation of relative activity from state to state. More information is available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/main.html.
      During week 5, the following ILI activity levels were experienced:


      *This map uses the proportion of outpatient visits to health care providers for ILI to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
      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.
      Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map is based on reports from state and territorial epidemiologists. The data presented in this map are preliminary and may change as more data are received.
      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.


      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. Additional data displaying the influenza activity reported by state and territorial epidemiologists for the current and past seasons are available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/FluView8.html
      During week 5, the following influenza activity was reported:
        • New York City and 24 states (Alabama, Alaska, Arkansas, Colorado, Connecticut, Georgia, Indiana, Kansas, Kentucky, Massachusetts, Mississippi, Nebraska, New Jersey, New Mexico, North Carolina, Oklahoma, Rhode Island, South Carolina, South Dakota, Texas, Utah, Vermont, Virginia and West Virginia) experienced high ILI activity.
        • Puerto Rico and 10 states (Arizona, California, Hawaii, Illinois, Louisiana, Missouri, New York, North Dakota, Pennsylvania, and Tennessee) experienced moderate ILI activity.
        • The District of Columbia and 13 states (Florida, Idaho, Iowa, Maine, Maryland, Michigan, Minnesota, Montana, Nevada, New Hampshire, Oregon, Washington, and Wisconsin) experienced low ILI activity.
        • Three states (Delaware, Ohio, and Wyoming) experienced minimal ILI activity.
        • Widespread influenza activity was reported by Puerto Rico and 47 states (Alabama, 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, Wisconsin and Wyoming).
        • Regional influenza activity was reported by two states (Alaska and West Virginia).
        • Local influenza activity was reported by the District of Columbia and one state (Hawaii).
        • Sporadic influenza activity was reported by the U.S. Virgin Islands.
        • Guam did not report.
          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 5,791 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2018 and February 2, 2019. The overall hospitalization rate was 20.1 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 (53.0 per 100,000 population), followed by children aged 0-4 (33.5 per 100,000 population) and adults aged 50-64 (27.2 per 100,000 population). Among 5,791 hospitalizations, 5,434 (93.8%) were associated with influenza A virus, 299 (5.2%) with influenza B virus, 28 (0.5%) with influenza A virus and influenza B virus co-infection, and 30 (0.5%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 975 (76.8%) were A(H1N1)pdm09 virus and 294 (23.2%) were A(H3N2).
          Among 755 hospitalized adults with information on underlying medical conditions, 681 (90.2%) had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, obesity, and metabolic disorder. Among 150 hospitalized children with information on underlying medical conditions, 62 (41.33%) had at least one underlying medical condition; the most commonly reported was asthma. Among 131 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 20 (15.3%) were pregnant.
          Additional FluSurv-NET data displaying hospitalization rates for the current and past seasons and different age groups, as well as data on patient characteristics (such as influenza virus type, demographic, and clinical information), are available on FluView Interactive at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.
          FluSurv-Net data is used to generate national estimates of the total numbers of flu cases, medical visits, and hospitalizations. This season, CDC is reporting preliminary cumulative in-season estimates, which are available at https://cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm.
          Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
          View Interactive Application | View Full Screen | View PowerPoint Presentation
          FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancy percentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
          View Interactive Application | View Full Screen | View PowerPoint Presentation

          Pneumonia and Influenza (P&I) Mortality Surveillance:

          Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 7, 2019, 6.9% of the deaths occurring during the week ending January 26, 2019 (week 4) were due to P&I. This percentage is below the epidemic threshold of 7.2% for week 4.
          Additional pneumonia and influenza mortality data for current and past seasons and by geography (national, HHS region, or state) are available at on FluView Interactive http://gis.cdc.gov/grasp/fluview/mortality.html. Data displayed on the regional and state-level are aggregated by the state of residence of the decedent.

          View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation

          Influenza-Associated Pediatric Mortality:

          Four influenza-associated pediatric deaths were reported to CDC during week 5. Two deaths were associated with an influenza A(H1N1)pdm09 virus and occurred during weeks 4 and 5 (the weeks ending January 26 and February 2, 2019, respectively). Two deaths were associated with an influenza A virus for which no subtyping was performed and occurred during weeks 4 and 5.
          A total of 28 influenza-associated pediatric deaths occurring during the 2018-2019 season have been reported to CDC.
          Additional information on influenza-associated pediatric deaths including basic demographics, underlying conditions, bacterial co-infections, and place of death for the current and past seasons, is available on FluView Interactivehttp://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

          View Interactive Application | View Full Screen | View PowerPoint Presentation


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

          World Health Organization: Additional influenza surveillance information from participating WHO member nations is available throughFluNet 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 athttps://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.
            --------------------------------------------------------------------------------
    https://www.cdc.gov/flu/weekly/index.htm
    Twitter: @RonanKelly13
    The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

    Comment


    • #17
      2018-2019 Influenza Season Week 6 ending February 9, 2019

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

      Influenza activity continues to increase in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending February 9, 2019:
      • Viral Surveillance:The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories increased. Influenza A(H1N1)pdm09 viruses have predominated in most areas of the country, however influenza A(H3) viruses have predominated in the southeastern United States (HHS Region 4). In the most recent three weeks, influenza A(H1N1)pdm09 and influenza A(H3) viruses were reported in approximately equal numbers in HHS Regions 6 and 7.
        • Virus Characterization:The majority of influenza viruses characterized antigenically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
        • Antiviral Resistance:The vast majority of influenza viruses tested (>99%) show susceptibility to oseltamivir and peramivir. All influenza viruses tested showed susceptibility to zanamivir.
      • Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) increased to 4.8%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
        • ILI State Activity Indictor Map: New York City and 26 states experienced high ILI activity; the District of Columbia, Puerto Rico and eight states experienced moderate ILI activity; 11 states experienced low ILI activity; and the U.S. Virgin Islands and five states experienced minimal ILI activity.
      • Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 48 states was reported as widespread; one state reported regional activity; the District of Columbia and one state reported local activity; the U.S. Virgin Islands reported sporadic activity; and Guam did not report.
      • Influenza-associated Hospitalizations A cumulative rate of 23.8 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (64.1 hospitalizations per 100,000 population).
      • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
      • Influenza-associated Pediatric Deaths: Six influenza-associated pediatric deaths were reported to CDC during week 6.
      National and Regional Summary of Select Surveillance Components

      Elevated 50 of 54 24.6% Influenza A(H1N1)pdm09
      Elevated 6 of 6 26.3% Influenza A(H1N1)pdm09
      Elevated 3 of 4 22.6% Influenza A(H1N1)pdm09
      Elevated 5 of 6 22.4% Influenza A(H1N1)pdm09
      Elevated 8 of 8 17.6% Influenza A(H3)
      Elevated 6 of 6 19.3% Influenza A(H1N1)pdm09
      Elevated 5 of 5 29.9% Approximately equal Influenza A(H1N1)pdm09 and Influenza A(H3)
      Elevated 4 of 4 20.1% Approximately equal Influenza A(H1N1)pdm09 and Influenza A(H3)
      Elevated 6 of 6 27.1% Influenza A(H1N1)pdm09
      Elevated 3 of 5 13.0% Influenza A(H1N1)pdm09
      Elevated 4 of 4 19.7% Influenza A(H1N1)pdm09
      *https://www.hhs.gov/about/agencies/i...ces/index.html
      † Elevated means the % of visits for ILI is at or above the national or region-specific baseline
      § Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands
      ‡ National data are for current week; regional data are for the most recent three weeks


      U.S. Virologic Surveillance:

      WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, Guam, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza by virus type. In addition, public health laboratories also report the influenza A subtype (H1 or H3) and influenza B lineage information of the viruses they test and the age or age group of the persons from whom the specimens were collected.
      Additional virologic data, including national, regional and select state-level data, can be found at: http://gis.cdc.gov/grasp/fluview/flu...dashboard.html. Age group proportions and totals by influenza subtype reported by public health laboratories can be found at: http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.
      The results of tests performed by clinical laboratories are summarized below.
      38,350 587,279
      9,428 (24.6%) 67,119 (11.4%)
      9,218 (97.8%) 64,385 (95.9%)
      210 (2.2%) 2,734 (4.1%)

      View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
      The results of tests performed by public health laboratories are summarized below.
      1,731 33,772
      1,046 14,439
      1,029 (98.4%) 14,056 (97.3%)
      649 (64.5%) 10,545 (78.5%)
      357 (35.5%) 2,887 (21.5%)
      23 624
      17 (1.6%) 383 (2.7%)
      2 (20.0%) 161 (56.1%)
      8 (80.0%) 126 (43.9%)
      7 96
      *The percent of specimens testing positive for influenza is not reported because public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory and therefore percent positive would not be a valid indicator of influenza activity. Additional information is available at http://www.cdc.gov/flu/weekly/overview.htm.


      View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
      Influenza Virus Characterization:

      Close monitoring of influenza viruses is required to better assess the potential impact on public health. CDC characterizes influenza viruses through one or more tests including genomic sequencing, hemagglutination inhibition (HI) and/or neutralization based Focus Reduction assays (FRA). These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. Antigenic and genetic characterization of circulating influenza viruses gives an indication of the influenza vaccine's ability to induce an immune response against the wide array of influenza viruses that are co-circulating every season. However, annual vaccine effectiveness estimates are needed to determine how much protection was provided to the population by vaccination. On February 14, 2019, interim influenza effectiveness estimates for the 2018-2019 season were released and are available here.
      For nearly all influenza-positive surveillance samples received at CDC, next-generation sequencing is performed to determine the genetic identity of circulating influenza viruses and to monitor the evolutionary trajectory of viruses circulating in our population. Virus gene segments are classified into genetic clades/subclades based on phylogenetic analysis. However, genetic changes that classify the clades/subclades do not always result in antigenic changes. “Antigenic drift” is a term used to describe gradual antigenic change that occurs as viruses evolve changes to escape host immune pressure. 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 has antigenically or genetically characterized 968 influenza viruses collected September 30, 2018 – February 9, 2019, and submitted by U.S. laboratories, including 554 influenza A(H1N1)pdm09 viruses, 308 influenza A(H3N2) viruses, and 106 influenza B viruses.
      Influenza A Viruses
      Influenza B Viruses

      The majority of U.S. viruses submitted for characterization come from state and local public health laboratories. Due to Right Size Roadmapconsiderations, specimen submission guidance to laboratories is that, if available, 2 influenza A(H1N1)pdm09, 2 influenza A(H3N2), and 2 influenza B viruses be submitted every other week. Therefore, the numbers of each virus type/subtype characterized should be more balanced across subtypes/lineages but will not reflect the actual proportion of circulating viruses. In the figure below, the results of tests performed by public health labs are shown on the left and CDC sequence results (by genetic clade/subclade) are shown on the right.

      View Chart Data | View Full Screen | View PowerPoint Presentation
        • A (H1N1)pdm09: Phylogenetic analysis of the HA genes from 554 A(H1N1)pdm09 viruses showed that all belonged to clade 6B.1. One hundred ninety four A(H1N1)pdm09 viruses were antigenically characterized, and 191 (98.5%) were antigenically similar (analyzed using HI with ferret antisera) to A/Michigan/45/2015 (6B.1), a cell-propagated A/Michigan/45/2015-like reference virus representing the A(H1N1)pdm09 component for the 2018-19 Northern Hemisphere influenza vaccines.
        • A (H3N2): Phylogenetic analysis of the HA genes from 308 A(H3N2) viruses revealed extensive genetic diversity with multiple clades/subclades co-circulating. The HA genes of circulating viruses belonged to clade 3C.2a (n=61), subclade 3C.2a1 (n=109) or clade 3C.3a (n=138). One hundred ninety-four A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 128 (66%) A(H3N2) viruses tested were well-inhibited (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera raised against A/Singapore/INFIMH-16-0019/2016 (3C.2a1), a cell-propagated reference virus representing the A(H3N2) component of 2018-19 Northern Hemisphere influenza vaccines. Sixty-six (34%) viruses reacted poorly (at titers that were 8-fold or greater reduced compared with that of the homologous virus A/Singapore/INFIMH-16-0019/2016) and of those, 65 (98.5%) belonged to clade 3C.3a.
        • B/Victoria: Phylogenetic analysis of 40 B/Victoria-lineage viruses indicate that all HA genes belonged to genetic clade V1A, however genetic subclades which are antigenically distinct have emerged. Genetic subclades which are antigenically distinct include viruses with a two amino acid deletion (162-163) in the HA protein (V1A.1, previously abbreviated as V1A-2Del) and viruses with a three amino acid deletion (162-164) in the HA protein (abbreviated as V1A-3Del). Twenty-one B/Victoria lineage viruses were antigenically characterized and 15 (71.4%) were antigenically similar with ferret antisera raised against cell-propagated B/Colorado/06/2017-like V1A.1 reference virus. Six (28.6%) reacted poorly (at titers that were 8-fold or greater reduced compared with the homologous virus titer) and belonged to clade V1A.
        • B/Yamagata: Phylogenetic analysis of 66 influenza B/Yamagata-lineage viruses indicate that the HA genes belonged to clade Y3. A total of 53 influenza B/Yamagata-lineage viruses were antigenically characterized, and all were antigenically similar to cell-propagated B/Phuket/3073/2013 (Y3), the reference vaccine virus representing the influenza B/Yamagata-lineage component of the 2018-19 Northern Hemisphere quadrivalent vaccines.
        Antiviral Resistance:

        Testing of influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses for resistance to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using next-generation sequencing analysis and/or a functional assay. Neuraminidase sequences of viruses are inspected to detect the presence of amino acid substitutions,previously associated with reduced or highly reduced inhibition by any of three neuraminidase inhibitors.In addition, a subset of viruses are tested using the neuraminidase inhibition assay with three neuraminidase inhibitors. The level of neuraminidase activity inhibition is reported using the thresholds recommended by the World Health Organization Expert Working Group of the Global Influenza Surveillance and Response System (GISRS)These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with an antiviral-resistant virus.
        Reporting of baloxavir susceptibility testing for the 2018-2019 influenza season will begin later this season. More information regarding influenza antiviral drug resistance can be found here.
        High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.
        Assessment of Virus Susceptibility to Neuraminidase Inhibitors Using Next-Generation Sequencing Analysis and/or Neuraminidase Inhibition Assay

        Oseltamivir Peramivir Zanamivir
        823 2 (0.2%) 2 (0.2%) 823 0 (0%) 2 (0.2%) 823 0 (0%) 0 (0%)
        481 2 (0.4%) 2 (0.4%) 481 0 (0%) 2 (0.4%) 481 0 (0%) 0 (0%)
        254 0 (0%) 0 (0%) 254 0 (0%) 0 (0%) 254 0 (0%) 0 (0%)
        34 0 (0%) 0 (0%) 34 0 (0%) 0 (0%) 34 0 (0%) 0 (0%)
        54 0 (0%) 0 (0%) 54 0 (0%) 0 (0%) 54 0 (0%) 0 (0%)
        Antiviral treatment as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at:http://www.cdc.gov/flu/antivirals/index.htm.



        Outpatient Illness Surveillance:

        Nationwide during week 6, 4.8% 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 2.2%.(ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
        On a regional level, the percentage of outpatient visits for ILI ranged from 2.4% to 9.8% during week 6. All 10 regions reported a percentage of outpatient visits for ILI at or above their region-specific baseline.
        Additional data on medically attended visits for ILI for current and past seasons and by geography (national, HHS region, or select states) are available on FluView Interactive http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

        View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation



        ILINet State Activity Indicator Map:

        Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below, or only slightly above, the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.
        The ILI Activity Indicator Map displays state-specific activity levels for multiple seasons and allows a visual representation of relative activity from state to state. More information is available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/main.html.
        During week 6, the following ILI activity levels were experienced:


        *This map uses the proportion of outpatient visits to health care providers for ILI to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
        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.
        Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map is based on reports from state and territorial epidemiologists. The data presented in this map are preliminary and may change as more data are received.
        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.


        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. Additional data displaying the influenza activity reported by state and territorial epidemiologists for the current and past seasons are available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/FluView8.html
        During week 6, the following influenza activity was reported:
          • New York City and 26 states (Alabama, Arizona, Arkansas, Colorado, Georgia, Idaho, Indiana, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Rhode Island, South Carolina, Tennessee, Texas, Utah, and Virginia) experienced high ILI activity.
          • The District of Columbia, Puerto Rico and eight states (Connecticut, Maine, Montana, Oregon, Pennsylvania, Vermont, West Virginia and Wyoming) experienced moderate ILI activity.
          • 11 states (California, Delaware, Florida, Hawaii, Illinois, Iowa, Minnesota, Nevada, New Hampshire, North Dakota, and South Dakota) experienced low ILI activity.
          • The U.S. Virgin Islands and five states (Alaska, Michigan, Ohio, Washington and Wisconsin) experienced minimal ILI activity.
          • Widespread influenza activity was reported by 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, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, Wisconsin and Wyoming).
          • Regional influenza activity was reported by one state (West Virginia).
          • Local influenza activity was reported by the District of Columbia and one state (Hawaii).
          • Sporadic influenza activity was reported by the U.S. Virgin Islands.
          • Guam did not report.
            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 6,868 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2018 and February 9, 2019. The overall hospitalization rate was 23.8 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 (64.1 per 100,000 population), followed by children aged 0-4 (36.8 per 100,000 population) and adults aged 50-64 (32.5 per 100,000 population). Among 6,868 hospitalizations, 6,483 (94.4%) were associated with influenza A virus, 319 (4.6%) with influenza B virus, 31 (0.5%) with influenza A virus and influenza B virus co-infection, and 35 (0.5%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,130 (75.2%) were A(H1N1)pdm09 virus and 372 (24.8%) were A(H3N2).
            Among 995 hospitalized adults with information on underlying medical conditions, 902 (90.7%) had at least one reported underlying medical condition, the most commonly reported were obesity, metabolic disorder, and cardiovascular disease. Among 206 hospitalized children with information on underlying medical conditions, 88 (42.7%) had at least one underlying medical condition; the most commonly reported was asthma. Among 168 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 28 (16.7%) were pregnant.
            Additional FluSurv-NET data displaying hospitalization rates for the current and past seasons and different age groups, as well as data on patient characteristics (such as influenza virus type, demographic, and clinical information), are available on FluView Interactive at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.
            FluSurv-Net data is used to generate national estimates of the total numbers of flu cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available athttps://cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm.
            Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
            View Interactive Application | View Full Screen | View PowerPoint Presentation
            FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancy percentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
            View Interactive Application | View Full Screen | View PowerPoint Presentation

            Pneumonia and Influenza (P&I) Mortality Surveillance:

            Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 14, 2019, 7.0% of the deaths occurring during the week ending February 2, 2019 (week 5) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 5.
            Additional pneumonia and influenza mortality data for current and past seasons and by geography (national, HHS region, or state) are available at on FluView Interactive http://gis.cdc.gov/grasp/fluview/mortality.html. Data displayed on the regional and state-level are aggregated by the state of residence of the decedent.

            View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation

            Influenza-Associated Pediatric Mortality:

            Six influenza-associated pediatric deaths were reported to CDC during week 6. Two deaths were associated with an influenza A(H1N1)pdm09 virus and occurred during weeks 5 and 6 (the weeks ending February 2 and February 9, 2019, respectively). Four deaths were associated with an influenza A virus for which no subtyping was performed and occurred during weeks 4, 5, and 6 (the weeks ending January 26, February 2 and February 9, 2019, respectively).
            A total of 34 influenza-associated pediatric deaths occurring during the 2018-2019 season have been reported to CDC.
            Additional information on influenza-associated pediatric deaths including basic demographics, underlying conditions, bacterial co-infections, and place of death for the current and past seasons, is available on FluView Interactivehttp://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

            View Interactive Application | View Full Screen | View PowerPoint Presentation


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

            World Health Organization: Additional influenza surveillance information from participating WHO member nations is available throughFluNet 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 athttps://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.
              --------------------------------------------------------------------------------
      https://www.cdc.gov/flu/weekly/index.htm
      Twitter: @RonanKelly13
      The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

      Comment


      • #18
        2018-2019 Influenza Season Week 7 ending February 16, 2019

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

        Influenza activity continues to increase in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending February 16, 2019:
        • Viral Surveillance:The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories increased. While influenza A(H1N1)pdm09 viruses predominated in most areas of the country, influenza A(H3) viruses have predominated in HHS Region 4 and accounted for 47% of subtyped influenza A viruses detected nationally during week 7. During the most recent three weeks, influenza A(H3) viruses were reported more frequently than influenza A(H1N1)pdm09 viruses in HHS Regions 6 and 7 and influenza A(H1N1)pdm09 and influenza A(H3) viruses were reported in approximately equal numbers in HHS Region 2.
          • Virus Characterization:The majority of influenza viruses characterized antigenically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
          • Antiviral Resistance:The vast majority of influenza viruses tested (>99%) show susceptibility to oseltamivir and peramivir. All influenza viruses tested showed susceptibility to zanamivir.
        • Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) increased to 5.1%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
          • ILI State Activity Indictor Map: New York City and 30 states experienced high ILI activity; the District of Columbia and 11 states experienced moderate ILI activity; six states experienced low ILI activity; the U.S. Virgin Islands and three states experienced minimal ILI activity; and Puerto Rico had insufficient data.
        • Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 48 states was reported as widespread; one state reported regional activity; the District of Columbia reported local activity; the U.S. Virgin Islands and one state reported sporadic activity; and Guam did not report.
        • Influenza-associated Hospitalizations A cumulative rate of 27.4 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (75.6 hospitalizations per 100,000 population).
        • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
        • Influenza-associated Pediatric Deaths: Seven influenza-associated pediatric deaths were reported to CDC during week 7.
        National and Regional Summary of Select Surveillance Components

        Elevated 50 of 54 26.7% Influenza A(H1N1)pdm09
        Elevated 6 of 6 25.9% Influenza A(H1N1)pdm09
        Elevated 3 of 4 24.6% Approximately equal Influenza A(H1N1)pdm09 and Influenza A(H3)
        Elevated 5 of 6 24.1% Influenza A(H1N1)pdm09
        Elevated 8 of 8 19.5% Influenza A(H3)
        Elevated 6 of 6 22.3% Influenza A(H1N1)pdm09
        Elevated 5 of 5 32.5% Influenza A(H3)
        Elevated 4 of 4 23.8% Influenza A(H3)
        Elevated 6 of 6 30.3% Influenza A(H1N1)pdm09
        Elevated 3 of 5 12.9% Influenza A(H1N1)pdm09
        Elevated 4 of 4 24.5% Influenza A(H1N1)pdm09
        *https://www.hhs.gov/about/agencies/i...ces/index.html
        † Elevated means the % of visits for ILI is at or above the national or region-specific baseline
        § Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands
        ‡ National data are for current week; regional data are for the most recent three weeks


        U.S. Virologic Surveillance:

        WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, Guam, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza by virus type. In addition, public health laboratories also report the influenza A subtype (H1 or H3) and influenza B lineage information of the viruses they test and the age or age group of the persons from whom the specimens were collected.
        Additional virologic data, including national, regional and select state-level data, can be found at: http://gis.cdc.gov/grasp/fluview/flu...dashboard.html. Age group proportions and totals by influenza subtype reported by public health laboratories can be found at: http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.
        The results of tests performed by clinical laboratories are summarized below.
        38,208 639,225
        10,210 (26.7%) 80,755 (12.6%)
        9,936 (97.3%) 77,625 (96.1%)
        274 (2.7%) 3,130 (3.9%)

        View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
        The results of tests performed by public health laboratories are summarized below.
        1,792 40,074
        1,075 18,076
        1,058 (98.4%) 17,636 (97.6%)
        529 (53.1%) 12,720 (75.4%)
        467 (46.9%) 4,142 (24.6%)
        62 774
        17 (1.6%) 440 (2.4%)
        3 (30.0%) 178 (55.3%)
        7 (70.0%) 144 (44.7%)
        7 118
        *The percent of specimens testing positive for influenza is not reported because public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory and therefore percent positive would not be a valid indicator of influenza activity. Additional information is available at http://www.cdc.gov/flu/weekly/overview.htm.


        View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
        Influenza Virus Characterization:

        Close monitoring of influenza viruses is required to better assess the potential impact on public health. CDC characterizes influenza viruses through one or more tests including genomic sequencing, hemagglutination inhibition (HI) and/or neutralization based Focus Reduction assays (FRA). These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. Antigenic and genetic characterization of circulating influenza viruses gives an indication of the influenza vaccine's ability to induce an immune response against the wide array of influenza viruses that are co-circulating every season. However, annual vaccine effectiveness estimates are needed to determine how much protection was provided to the population by vaccination. On February 14, 2019, interim influenza effectiveness estimates for the 2018-2019 season were released and are available here.
        For nearly all influenza-positive surveillance samples received at CDC, next-generation sequencing is performed to determine the genetic identity of circulating influenza viruses and to monitor the evolutionary trajectory of viruses circulating in our population. Virus gene segments are classified into genetic clades/subclades based on phylogenetic analysis. However, genetic changes that classify the clades/subclades do not always result in antigenic changes. “Antigenic drift” is a term used to describe gradual antigenic change that occurs as viruses evolve changes to escape host immune pressure. 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 has antigenically or genetically characterized 1,129 influenza viruses collected September 30, 2018 – February 16, 2019, and submitted by U.S. laboratories, including 626 influenza A(H1N1)pdm09 viruses, 381 influenza A(H3N2) viruses, and 122 influenza B viruses.
        Influenza A Viruses
        Influenza B Viruses

        The majority of U.S. viruses submitted for characterization come from state and local public health laboratories. Due to Right Size Roadmapconsiderations, specimen submission guidance to laboratories is that, if available, 2 influenza A(H1N1)pdm09, 2 influenza A(H3N2), and 2 influenza B viruses be submitted every other week. Therefore, the numbers of each virus type/subtype characterized should be more balanced across subtypes/lineages but will not reflect the actual proportion of circulating viruses. In the figure below, the results of tests performed by public health labs are shown on the left and CDC sequence results (by genetic clade/subclade) are shown on the right.

        View Chart Data | View Full Screen | View PowerPoint Presentation
          • A (H1N1)pdm09: Phylogenetic analysis of the HA genes from 626 A(H1N1)pdm09 viruses showed that all belonged to clade 6B.1. Two hundred sixty-three A(H1N1)pdm09 viruses were antigenically characterized, and 259 (98.5%) were antigenically similar (analyzed using HI with ferret antisera) to A/Michigan/45/2015 (6B.1), a cell-propagated A/Michigan/45/2015-like reference virus representing the A(H1N1)pdm09 component for the 2018-19 Northern Hemisphere influenza vaccines.
          • A (H3N2): Phylogenetic analysis of the HA genes from 381 A(H3N2) viruses revealed extensive genetic diversity with multiple clades/subclades co-circulating. The HA genes of circulating viruses belonged to clade 3C.2a (n=62), subclade 3C.2a1 (n=122) or clade 3C.3a (n=197). One hundred ninety-four A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 128 (66%) A(H3N2) viruses tested were well-inhibited (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera raised against A/Singapore/INFIMH-16-0019/2016 (3C.2a1), a cell-propagated reference virus representing the A(H3N2) component of 2018-19 Northern Hemisphere influenza vaccines. Sixty-six (34%) viruses reacted poorly (at titers that were 8-fold or greater reduced compared with that of the homologous virus A/Singapore/INFIMH-16-0019/2016) and of those, 65 (98.5%) belonged to clade 3C.3a.
          • B/Victoria: Phylogenetic analysis of 48 B/Victoria-lineage viruses indicate that all HA genes belonged to genetic clade V1A, however genetic subclades which are antigenically distinct have emerged. Genetic subclades which are antigenically distinct include viruses with a two amino acid deletion (162-163) in the HA protein (V1A.1, previously abbreviated as V1A-2Del) and viruses with a three amino acid deletion (162-164) in the HA protein (abbreviated as V1A-3Del). Forty B/Victoria lineage viruses were antigenically characterized and 33 (82.5%) were antigenically similar with ferret antisera raised against cell-propagated B/Colorado/06/2017-like V1A.1 reference virus. Seven (17.5%) reacted poorly (at titers that were 8-fold or greater reduced compared with the homologous virus titer) and belonged to clade V1A.
          • B/Yamagata: Phylogenetic analysis of 74 influenza B/Yamagata-lineage viruses indicate that the HA genes belonged to clade Y3. A total of 53 influenza B/Yamagata-lineage viruses were antigenically characterized, and all were antigenically similar to cell-propagated B/Phuket/3073/2013 (Y3), the reference vaccine virus representing the influenza B/Yamagata-lineage component of the 2018-19 Northern Hemisphere quadrivalent vaccines.
          Antiviral Resistance:

          Testing of influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses for resistance to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using next-generation sequencing analysis and/or a functional assay. Neuraminidase sequences of viruses are inspected to detect the presence of amino acid substitutions,previously associated with reduced or highly reduced inhibition by any of three neuraminidase inhibitors.In addition, a subset of viruses are tested using the neuraminidase inhibition assay with three neuraminidase inhibitors. The level of neuraminidase activity inhibition is reported using the thresholds recommended by the World Health Organization Expert Working Group of the Global Influenza Surveillance and Response System (GISRS)These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with an antiviral-resistant virus.
          Reporting of baloxavir susceptibility testing for the 2018-2019 influenza season will begin later this season. More information regarding influenza antiviral drug resistance can be found here.
          High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.
          Assessment of Virus Susceptibility to Neuraminidase Inhibitors Using Next-Generation Sequencing Analysis and/or Neuraminidase Inhibition Assay

          Oseltamivir Peramivir Zanamivir
          1,115 2 (0.2%) 2 (0.2%) 1,115 0 (0%) 2 (0.2%) 1,115 0 (0%) 0 (0%)
          619 2 (0.3%) 2 (0.3%) 619 0 (0%) 2 (0.3%) 619 0 (0%) 0 (0%)
          375 0 (0%) 0 (0%) 375 0 (0%) 0 (0%) 375 0 (0%) 0 (0%)
          46 0 (0%) 0 (0%) 46 0 (0%) 0 (0%) 46 0 (0%) 0 (0%)
          75 0 (0%) 0 (0%) 75 0 (0%) 0 (0%) 75 0 (0%) 0 (0%)
          Antiviral treatment as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at:http://www.cdc.gov/flu/antivirals/index.htm.



          Outpatient Illness Surveillance:

          Nationwide during week 7, 5.1% 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 2.2%.(ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
          On a regional level, the percentage of outpatient visits for ILI ranged from 2.5% to 10.1% during week 7. All 10 regions reported a percentage of outpatient visits for ILI at or above their region-specific baseline.
          Additional data on medically attended visits for ILI for current and past seasons and by geography (national, HHS region, or select states) are available on FluView Interactive http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

          View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation



          ILINet State Activity Indicator Map:

          Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below, or only slightly above, the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.
          The ILI Activity Indicator Map displays state-specific activity levels for multiple seasons and allows a visual representation of relative activity from state to state. More information is available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/main.html.
          During week 7, the following ILI activity levels were experienced:


          *This map uses the proportion of outpatient visits to health care providers for ILI to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
          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.
          Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map is based on reports from state and territorial epidemiologists. The data presented in this map are preliminary and may change as more data are received.
          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.


          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. Additional data displaying the influenza activity reported by state and territorial epidemiologists for the current and past seasons are available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/FluView8.html
          During week 7, the following influenza activity was reported:
            • New York City and 30 states (Alabama, Alaska, Arkansas, Colorado, Georgia, Indiana, Kansas, Kentucky, Louisiana, Maine, Massachusetts, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, and Wyoming) experienced high ILI activity.
            • The District of Columbia and 11 states (Arizona, California, Connecticut, Delaware, Hawaii, Idaho, Illinois, Iowa, Maryland, Montana and Oregon) experienced moderate ILI activity.
            • Six states (Florida, Michigan, Nevada, North Dakota, South Dakota and Wisconsin) experienced low ILI activity.
            • The U.S. Virgin Islands and three states (Minnesota, New Hampshire and Ohio) experienced minimal ILI activity.
            • Data were insufficient to calculate an ILI activity level from Puerto Rico.
            • Widespread influenza activity was reported by 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, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, Wisconsin and Wyoming).
            • Regional influenza activity was reported by one state (West Virginia).
            • Local influenza activity was reported by the District of Columbia.
            • Sporadic influenza activity was reported by the U.S. Virgin Islands and one state (Hawaii).
            • Guam did not report.
              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 7,922 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2018 and February 16, 2019. The overall hospitalization rate was 27.4 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 (75.6 per 100,000 population), followed by children aged 0-4 (40.2 per 100,000 population) and adults aged 50-64 (37.7 per 100,000 population). Among 7,922 hospitalizations, 7,509 (94.8%) were associated with influenza A virus, 340 (4.3%) with influenza B virus, 31 (0.4%) with influenza A virus and influenza B virus co-infection, and 42 (0.5%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,245 (72.4%) were A(H1N1)pdm09 virus and 474 (27.6%) were A(H3N2).
              Among 1,169 hospitalized adults with information on underlying medical conditions, 1,602 (90.9%) had at least one reported underlying medical condition, the most commonly reported were obesity, metabolic disorder, and cardiovascular disease. Among 230 hospitalized children with information on underlying medical conditions, 99 (43.04%) had at least one underlying medical condition; the most commonly reported was asthma. Among 191 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 34 (17.8%) were pregnant.
              Additional FluSurv-NET data displaying hospitalization rates for the current and past seasons and different age groups, as well as data on patient characteristics (such as influenza virus type, demographic, and clinical information), are available on FluView Interactive at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.
              FluSurv-Net data is used to generate national estimates of the total numbers of flu cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available athttps://cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm.
              Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
              View Interactive Application | View Full Screen | View PowerPoint Presentation
              FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancy percentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
              View Interactive Application | View Full Screen | View PowerPoint Presentation

              Pneumonia and Influenza (P&I) Mortality Surveillance:

              Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 21, 2019, 7.0% of the deaths occurring during the week ending February 9, 2019 (week 6) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 6.
              Additional pneumonia and influenza mortality data for current and past seasons and by geography (national, HHS region, or state) are available at on FluView Interactive http://gis.cdc.gov/grasp/fluview/mortality.html. Data displayed on the regional and state-level are aggregated by the state of residence of the decedent.

              View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation

              Influenza-Associated Pediatric Mortality:

              Seven influenza-associated pediatric deaths were reported to CDC during week 7. Four deaths were associated with an influenza A(H1N1)pdm09 virus and occurred during weeks 2, 6, and 7 (the weeks ending January 12, February 9 and February 16, 2019, respectively). Two deaths were associated with an influenza A virus for which no subtyping was performed and occurred during weeks 5 and 6 (the weeks ending February 2 and February 9, 2019, respectively). One death was associated with an influenza B virus and occurred during week 52 (the week ending December 29, 2018).
              A total of 41 influenza-associated pediatric deaths occurring during the 2018-2019 season have been reported to CDC.
              Additional information on influenza-associated pediatric deaths including basic demographics, underlying conditions, bacterial co-infections, and place of death for the current and past seasons, is available on FluView Interactivehttp://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

              View Interactive Application | View Full Screen | View PowerPoint Presentation


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

              World Health Organization: Additional influenza surveillance information from participating WHO member nations is available throughFluNet 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 athttps://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.
                --------------------------------------------------------------------------------
        https://www.cdc.gov/flu/weekly/index.htm
        Twitter: @RonanKelly13
        The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

        Comment


        • #19
          2018-2019 Influenza Season Week 8 ending February 23, 2019

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

          Influenza activity remains elevated in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending February 23, 2019:
          • Viral Surveillance:The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories increased slightly. Nationally, during week 8, influenza A(H3) viruses were reported more frequently than influenza A(H1N1)pdm09 viruses. During the most recent three weeks, influenza A(H3) viruses were reported more frequently than influenza A(H1N1)pdm09 viruses in HHS Regions 2, 4, 6 and 7.
            • Virus Characterization:The majority of influenza viruses characterized antigenically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
            • Antiviral Resistance:The vast majority of influenza viruses tested (>99%) show susceptibility to oseltamivir and peramivir. All influenza viruses tested showed susceptibility to zanamivir.
          • Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) remained at 5.0%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
            • ILI State Activity Indictor Map: New York City and 33 states experienced high ILI activity; the District of Columbia and eight states experienced moderate ILI activity; Puerto Rico and eight states experienced low ILI activity; one state experienced minimal ILI activity; and the U.S. Virgin Islands had insufficient data.
          • Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 49 states was reported as widespread; the District of Columbia and one state reported local activity; the U.S. Virgin Islands reported sporadic activity; and Guam did not report.
          • Influenza-associated Hospitalizations A cumulative rate of 32.1 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (91.5 hospitalizations per 100,000 population).
          • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
          • Influenza-associated Pediatric Deaths: 15 influenza-associated pediatric deaths were reported to CDC during week 8.
          National and Regional Summary of Select Surveillance Components

          Elevated 50 of 54 26.4% Influenza A(H3)
          Elevated 6 of 6 23.9% Influenza A(H1N1)pdm09
          Elevated 3 of 4 27.0% Influenza A(H3)
          Elevated 5 of 6 26.3% Influenza A(H1N1)pdm09
          Elevated 8 of 8 19.6% Influenza A(H3)
          Elevated 6 of 6 25.2% Influenza A(H1N1)pdm09
          Elevated 5 of 5 31.9% Influenza A(H3)
          Elevated 4 of 4 26.2% Influenza A(H3)
          Elevated 6 of 6 33.2% Influenza A(H1N1)pdm09
          Elevated 3 of 5 12.6% Influenza A(H1N1)pdm09
          Elevated 4 of 4 25.3% Influenza A(H1N1)pdm09
          *https://www.hhs.gov/about/agencies/i...ces/index.html
          † Elevated means the % of visits for ILI is at or above the national or region-specific baseline
          § Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands

          U.S. Virologic Surveillance:

          WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, Guam, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza by virus type. In addition, public health laboratories also report the influenza A subtype (H1 or H3) and influenza B lineage information of the viruses they test and the age or age group of the persons from whom the specimens were collected.
          Additional virologic data, including national, regional and select state-level data, can be found at: http://gis.cdc.gov/grasp/fluview/flu...dashboard.html. Age group proportions and totals by influenza subtype reported by public health laboratories can be found at: http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.
          The results of tests performed by clinical laboratories are summarized below.
          39,107 688,818
          10,316 (26.4%) 93,220 (13.5%)
          10,027 (97.2%) 89,676 (96.2%)
          289 (2.8%) 3,544 (3.8%)

          View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
          The results of tests performed by public health laboratories are summarized below.
          1,915 44,359
          1,151 20,866
          1,128 (98.0%) 20,371 (97.6%)
          494 (45.9%) 14,101 (72.8%)
          583 (54.1%) 5,272 (27.2%)
          51 998
          23 (2.0%) 495 (2.4%)
          7 (50.0%) 192 (54.5%)
          7 (50.0%) 160 (45.5%)
          9 143
          *The percent of specimens testing positive for influenza is not reported because public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory and therefore percent positive would not be a valid indicator of influenza activity. Additional information is available at http://www.cdc.gov/flu/weekly/overview.htm.


          View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
          Influenza Virus Characterization:

          Close monitoring of influenza viruses is required to better assess the potential impact on public health. CDC characterizes influenza viruses through one or more tests including genomic sequencing, hemagglutination inhibition (HI) and/or neutralization based Focus Reduction assays (FRA). These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. Antigenic and genetic characterization of circulating influenza viruses gives an indication of the influenza vaccine's ability to induce an immune response against the wide array of influenza viruses that are co-circulating every season. However, annual vaccine effectiveness estimates are needed to determine how much protection was provided to the population by vaccination. On February 14, 2019, interim influenza effectiveness estimates for the 2018-2019 season were released and are available here.
          For nearly all influenza-positive surveillance samples received at CDC, next-generation sequencing is performed to determine the genetic identity of circulating influenza viruses and to monitor the evolutionary trajectory of viruses circulating in our population. Virus gene segments are classified into genetic clades/subclades based on phylogenetic analysis. However, genetic changes that classify the clades/subclades do not always result in antigenic changes. “Antigenic drift” is a term used to describe gradual antigenic change that occurs as viruses evolve changes to escape host immune pressure. 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 has antigenically or genetically characterized 1,258 influenza viruses collected September 30, 2018 – February 23, 2019, and submitted by U.S. laboratories, including 690 influenza A(H1N1)pdm09 viruses, 425 influenza A(H3N2) viruses, and 143 influenza B viruses.
          Influenza A Viruses
          Influenza B Viruses

          The majority of U.S. viruses submitted for characterization come from state and local public health laboratories. Due to Right Size Roadmapconsiderations, specimen submission guidance to laboratories is that, if available, 2 influenza A(H1N1)pdm09, 2 influenza A(H3N2), and 2 influenza B viruses be submitted every other week. Therefore, the numbers of each virus type/subtype characterized should be more balanced across subtypes/lineages but will not reflect the actual proportion of circulating viruses. In the figure below, the results of tests performed by public health labs are shown on the left and CDC sequence results (by genetic clade/subclade) are shown on the right.

          View Chart Data | View Full Screen | View PowerPoint Presentation
            • A (H1N1)pdm09: Phylogenetic analysis of the HA genes from 690 A(H1N1)pdm09 viruses showed that all belonged to clade 6B.1. Two hundred sixty four A(H1N1)pdm09 viruses were antigenically characterized, and 260 (98.5%) were antigenically similar (analyzed using HI with ferret antisera) to A/Michigan/45/2015 (6B.1), a cell-propagated A/Michigan/45/2015-like reference virus representing the A(H1N1)pdm09 component for the 2018-19 Northern Hemisphere influenza vaccines.
            • A (H3N2): Phylogenetic analysis of the HA genes from 425 A(H3N2) viruses revealed extensive genetic diversity with multiple clades/subclades co-circulating. The HA genes of circulating viruses belonged to clade 3C.2a (n=64), subclade 3C.2a1 (n=126) or clade 3C.3a (n=235). Two hundred and nine A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 132 (63.2%) A(H3N2) viruses tested were well-inhibited (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera raised against A/Singapore/INFIMH-16-0019/2016 (3C.2a1), a cell-propagated reference virus representing the A(H3N2) component of 2018-19 Northern Hemisphere influenza vaccines. Seventy-seven (36.8%) viruses reacted poorly (at titers that were 8-fold or greater reduced compared with that of the homologous virus A/Singapore/INFIMH-16-0019/2016) and of those, 76 (98.7%) belonged to clade 3C.3a.
            • B/Victoria: Phylogenetic analysis of 57 B/Victoria-lineage viruses indicate that all HA genes belonged to genetic clade V1A, however genetic subclades which are antigenically distinct have emerged. Genetic subclades which are antigenically distinct include viruses with a two amino acid deletion (162-163) in the HA protein (V1A.1, previously abbreviated as V1A-2Del) and viruses with a three amino acid deletion (162-164) in the HA protein (abbreviated as V1A-3Del). Forty B/Victoria lineage viruses were antigenically characterized and 33 (82.5%) were antigenically similar with ferret antisera raised against cell-propagated B/Colorado/06/2017-like V1A.1 reference virus. Seven (17.5%) reacted poorly (at titers that were 8-fold or greater reduced compared with the homologous virus titer) and belonged to clade V1A.
            • B/Yamagata: Phylogenetic analysis of 86 influenza B/Yamagata-lineage viruses indicate that the HA genes belonged to clade Y3. A total of 75 influenza B/Yamagata-lineage viruses were antigenically characterized, and all were antigenically similar to cell-propagated B/Phuket/3073/2013 (Y3), the reference vaccine virus representing the influenza B/Yamagata-lineage component of the 2018-19 Northern Hemisphere quadrivalent vaccines.
            Antiviral Resistance:

            Testing of influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses for resistance to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using next-generation sequencing analysis and/or a functional assay. Neuraminidase sequences of viruses are inspected to detect the presence of amino acid substitutions,previously associated with reduced or highly reduced inhibition by any of three neuraminidase inhibitors.In addition, a subset of viruses are tested using the neuraminidase inhibition assay with three neuraminidase inhibitors. The level of neuraminidase activity inhibition is reported using the thresholds recommended by the World Health Organization Expert Working Group of the Global Influenza Surveillance and Response System (GISRS)These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with an antiviral-resistant virus.
            Reporting of baloxavir susceptibility testing for the 2018-2019 influenza season will begin later this season. More information regarding influenza antiviral drug resistance can be found here.
            High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.
            Assessment of Virus Susceptibility to Neuraminidase Inhibitors Using Next-Generation Sequencing Analysis and/or Neuraminidase Inhibition Assay

            Oseltamivir Peramivir Zanamivir
            1,242 2 (0.2%) 2 (0.2%) 1,242 0 (0%) 2 (0.2%) 1,242 0 (0%) 0 (0%)
            684 2 (0.3%) 2 (0.3%) 684 0 (0%) 2 (0.3%) 684 0 (0%) 0 (0%)
            418 0 (0%) 0 (0%) 418 0 (0%) 0 (0%) 418 0 (0%) 0 (0%)
            54 0 (0%) 0 (0%) 54 0 (0%) 0 (0%) 54 0 (0%) 0 (0%)
            86 0 (0%) 0 (0%) 86 0 (0%) 0 (0%) 86 0 (0%) 0 (0%)
            Antiviral treatment as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at:http://www.cdc.gov/flu/antivirals/index.htm.



            Outpatient Illness Surveillance:

            Nationwide during week 8, 5.0% 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 2.2%.(ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
            On a regional level, the percentage of outpatient visits for ILI ranged from 3.0% to 9.4% during week 8. All 10 regions reported a percentage of outpatient visits for ILI at or above their region-specific baseline.
            Additional data on medically attended visits for ILI for current and past seasons and by geography (national, HHS region, or select states) are available on FluView Interactive http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

            View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation



            ILINet State Activity Indicator Map:

            Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below, or only slightly above, the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.
            The ILI Activity Indicator Map displays state-specific activity levels for multiple seasons and allows a visual representation of relative activity from state to state. More information is available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/main.html.
            During week 8, the following ILI activity levels were experienced:


            *This map uses the proportion of outpatient visits to health care providers for ILI to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
            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.
            Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map is based on reports from state and territorial epidemiologists. The data presented in this map are preliminary and may change as more data are received.
            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.


            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. Additional data displaying the influenza activity reported by state and territorial epidemiologists for the current and past seasons are available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/FluView8.html
            During week 8, the following influenza activity was reported:
              • New York City and 33 states (Alabama, Alaska, Arizona, Arkansas, Colorado, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Massachusetts, Mississippi, Missouri, Montana, Nebraska, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Utah, Virginia, West Virginia, and Wyoming) experienced high ILI activity.
              • The District of Columbia and eight states (California, Connecticut, Hawaii, Idaho, Iowa, Maine, South Dakota, and Vermont) experienced moderate ILI activity.
              • Puerto Rico and eight states (Delaware, Florida, Michigan, Minnesota, Ohio, Tennessee, Washington, and Wisconsin) experienced low ILI activity.
              • One state (New Hampshire) experienced minimal ILI activity.
              • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.
              • Widespread influenza activity was reported by 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).
              • Local influenza activity was reported by the District of Columbia and one state (Hawaii).
              • Sporadic influenza activity was reported by the U.S. Virgin Islands.
              • Guam did not report.
                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 9,274 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2018 and February 23, 2019. The overall hospitalization rate was 32.1 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 (91.5 per 100,000 population), followed by children aged 0-4 (45.5 per 100,000 population) and adults aged 50-64 (43.2 per 100,000 population). Among 9,274 hospitalizations, 8,810 (95.0%) were associated with influenza A virus, 386 (4.2%) with influenza B virus, 31 (0.3%) with influenza A virus and influenza B virus co-infection, and 47 (0.5%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,460 (69.7%) were A(H1N1)pdm09 virus and 634 (30.3%) were A(H3N2).
                Among 1,403 hospitalized adults with information on underlying medical conditions, 1,280 (91.2%) had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, and obesity. Among 265 hospitalized children with information on underlying medical conditions, 116 (43.8%) had at least one underlying medical condition; the most commonly reported was asthma. Among 223 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 46 (20.6%) were pregnant.
                Additional FluSurv-NET data displaying hospitalization rates for the current and past seasons and different age groups, as well as data on patient characteristics (such as influenza virus type, demographic, and clinical information), are available on FluView Interactive at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.
                FluSurv-Net data is used to generate national estimates of the total numbers of flu cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available athttps://cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm.
                Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
                View Interactive Application | View Full Screen | View PowerPoint Presentation
                FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancy percentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
                View Interactive Application | View Full Screen | View PowerPoint Presentation

                Pneumonia and Influenza (P&I) Mortality Surveillance:

                Based on National Center for Health Statistics (NCHS) mortality surveillance data available on February 28, 2019, 7.1% of the deaths occurring during the week ending February 16, 2019 (week 7) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 7.
                Additional pneumonia and influenza mortality data for current and past seasons and by geography (national, HHS region, or state) are available at on FluView Interactive http://gis.cdc.gov/grasp/fluview/mortality.html. Data displayed on the regional and state-level are aggregated by the state of residence of the decedent.

                View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation

                Influenza-Associated Pediatric Mortality:

                15 influenza-associated pediatric deaths were reported to CDC during week 8. Eight deaths were associated with an influenza A(H1N1)pdm09 virus and occurred during weeks 5, 6, 7 and 8 (the weeks ending February 2, February 9, February 16 and February 23, 2019, respectively). One death was associated with an influenza A(H3) virus and occurred during week 6 (the week ending February 9, 2019). Six deaths were associated with an influenza A virus for which no subtyping was performed and occurred during weeks 5, 6, 7 and 8.
                A total of 56 influenza-associated pediatric deaths occurring during the 2018-2019 season have been reported to CDC.
                Additional information on influenza-associated pediatric deaths including basic demographics, underlying conditions, bacterial co-infections, and place of death for the current and past seasons, is available on FluView Interactivehttp://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

                View Interactive Application | View Full Screen | View PowerPoint Presentation


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

                World Health Organization: Additional influenza surveillance information from participating WHO member nations is available throughFluNet 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 athttps://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.
                  --------------------------------------------------------------------------------
          https://www.cdc.gov/flu/weekly/index.htm
          Twitter: @RonanKelly13
          The views expressed are mine alone and do not represent the views of my employer or any other person or organization.

          Comment


          • #20
            2018-2019 Influenza Season Week 9 ending March 2, 2019

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

            Influenza activity remains elevated in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending March 2, 2019:
            • Viral Surveillance:The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories increased slightly. Nationally, during week 9, influenza A(H3) viruses were reported more frequently than influenza A(H1N1)pdm09 viruses. During the most recent three weeks, influenza A(H3) viruses were reported more frequently than influenza A(H1N1)pdm09 viruses in HHS Regions 2, 4, 6, 7 and 8.
              • Virus Characterization:The majority of influenza viruses characterized antigenically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
              • Antiviral Resistance:TThe vast majority of influenza viruses tested (>99%) show susceptibility to oseltamivir and peramivir. All influenza viruses tested showed susceptibility to zanamivir.
            • Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) decreased slightly to 4.7%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
              • ILI State Activity Indictor Map: 32 states experienced high ILI activity; Puerto Rico and seven states experienced moderate ILI activity; New York City, the District of Columbia and eight states experienced low ILI activity; three states experienced minimal ILI activity; and the U.S. Virgin Islands had insufficient data.
            • Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 48 states was reported as widespread; the District of Columbia and two states reported local activity; the U.S. Virgin Islands reported sporadic activity; and Guam did not report.
            • Influenza-associated Hospitalizations A cumulative rate of 36.6 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (107.7 hospitalizations per 100,000 population).
            • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was above the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
            • Influenza-associated Pediatric Deaths: Nine influenza-associated pediatric deaths were reported to CDC during week 9. Eight deaths occurred during the 2018-2019 season and one death occurred during the 2015-2016 season.
            National and Regional Summary of Select Surveillance Components

            Elevated 49 of 54 26.1% Influenza A(H3)
            Elevated 5 of 6 22.1% Influenza A(H1N1)pdm09
            Elevated 3 of 4 26.3% Influenza A(H3)
            Elevated 5 of 6 26.4% Influenza A(H1N1)pdm09
            Elevated 8 of 8 18.1% Influenza A(H3)
            Elevated 6 of 6 28.0% Influenza A(H1N1)pdm09
            Elevated 5 of 5 29.7% Influenza A(H3)
            Elevated 4 of 4 29.5% Influenza A(H3)
            Elevated 6 of 6 33.8% Influenza A(H3)
            Elevated 3 of 5 13.2% Influenza A(H1N1)pdm09
            Elevated 4 of 4 26.0% Influenza A(H1N1)pdm09
            *https://www.hhs.gov/about/agencies/i...ces/index.html
            † Elevated means the % of visits for ILI is at or above the national or region-specific baseline
            § Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands

            U.S. Virologic Surveillance:

            WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, Guam, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza by virus type. In addition, public health laboratories also report the influenza A subtype (H1 or H3) and influenza B lineage information of the viruses they test and the age or age group of the persons from whom the specimens were collected.
            Additional virologic data, including national, regional and select state-level data, can be found at: http://gis.cdc.gov/grasp/fluview/flu...dashboard.html. Age group proportions and totals by influenza subtype reported by public health laboratories can be found at: http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.
            The results of tests performed by clinical laboratories are summarized below.
            36,193 738,333
            9,434 (26.1%) 105,413 (14.3%)
            9,171 (97.2%) 101,414 (96.2%)
            263 (2.8%) 3,999 (3.8%)

            View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
            The results of tests performed by public health laboratories are summarized below.
            1,995 48,972
            1,209 23,837
            1,186 (98.1%) 23,284 (97.7%)
            429 (38.0%) 15,432 (69.6%)
            699 (62.0%) 6,725 (30.4%)
            58 1,127
            23 (1.9%) 553 (2.3%)
            2 (15.4%) 205 (52.3%)
            11 (84.6%) 187 (47.7%)
            10 161
            *The percent of specimens testing positive for influenza is not reported because public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory and therefore percent positive would not be a valid indicator of influenza activity. Additional information is available at http://www.cdc.gov/flu/weekly/overview.htm.


            View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
            Influenza Virus Characterization:

            Close monitoring of influenza viruses is required to better assess the potential impact on public health. CDC characterizes influenza viruses through one or more tests including genomic sequencing, hemagglutination inhibition (HI) and/or neutralization based Focus Reduction assays (FRA). These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. Antigenic and genetic characterization of circulating influenza viruses gives an indication of the influenza vaccine's ability to induce an immune response against the wide array of influenza viruses that are co-circulating every season. However, annual vaccine effectiveness estimates are needed to determine how much protection was provided to the population by vaccination. On February 14, 2019, interim influenza effectiveness estimates for the 2018-2019 season were released and are available here.
            For nearly all influenza-positive surveillance samples received at CDC, next-generation sequencing is performed to determine the genetic identity of circulating influenza viruses and to monitor the evolutionary trajectory of viruses circulating in our population. Virus gene segments are classified into genetic clades/subclades based on phylogenetic analysis. However, genetic changes that classify the clades/subclades do not always result in antigenic changes. “Antigenic drift” is a term used to describe gradual antigenic change that occurs as viruses evolve changes to escape host immune pressure. 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 has antigenically or genetically characterized 1,416 influenza viruses collected September 30, 2018 – March 2, 2019, and submitted by U.S. laboratories, including 762 influenza A(H1N1)pdm09 viruses, 490 influenza A(H3N2) viruses, and 164 influenza B viruses.
            Influenza A Viruses
            Influenza B Viruses

            The majority of U.S. viruses submitted for characterization come from state and local public health laboratories. Due to Right Size Roadmapconsiderations, specimen submission guidance to laboratories is that, if available, 2 influenza A(H1N1)pdm09, 2 influenza A(H3N2), and 2 influenza B viruses be submitted every other week. Therefore, the numbers of each virus type/subtype characterized should be more balanced across subtypes/lineages but will not reflect the actual proportion of circulating viruses. In the figure below, the results of tests performed by public health labs are shown on the left and CDC sequence results (by genetic clade/subclade) are shown on the right.

            View Chart Data | View Full Screen | View PowerPoint Presentation
              • A (H1N1)pdm09: Phylogenetic analysis of the HA genes from 762 A(H1N1)pdm09 viruses showed that all belonged to clade 6B.1. Two hundred sixty-four A(H1N1)pdm09 viruses were antigenically characterized, and 260 (98.5%) were antigenically similar (analyzed using HI with ferret antisera) to A/Michigan/45/2015 (6B.1), a cell-propagated A/Michigan/45/2015-like reference virus representing the A(H1N1)pdm09 component for the 2018-19 Northern Hemisphere influenza vaccines.
              • A (H3N2): Phylogenetic analysis of the HA genes from 490 A(H3N2) viruses revealed extensive genetic diversity with multiple clades/subclades co-circulating. The HA genes of circulating viruses belonged to clade 3C.2a (n=64), subclade 3C.2a1 (n=135) or clade 3C.3a (n=291). Two hundred twenty-four A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 138 (61.6%) A(H3N2) viruses tested were well-inhibited (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera raised against A/Singapore/INFIMH-16-0019/2016 (3C.2a1), a cell-propagated reference virus representing the A(H3N2) component of 2018-19 Northern Hemisphere influenza vaccines. Eighty-six (38.4%) viruses reacted poorly (at titers that were 8-fold or greater reduced compared with that of the homologous virus A/Singapore/INFIMH-16-0019/2016) and of those, 85 (98.8%) belonged to clade 3C.3a.
              • B/Victoria: Phylogenetic analysis of 67 B/Victoria-lineage viruses indicate that all HA genes belonged to genetic clade V1A, however genetic subclades which are antigenically distinct have emerged. Genetic subclades which are antigenically distinct include viruses with a two amino acid deletion (162-163) in the HA protein (V1A.1, previously abbreviated as V1A-2Del) and viruses with a three amino acid deletion (162-164) in the HA protein (abbreviated as V1A-3Del). Fifty-four B/Victoria lineage viruses were antigenically characterized and 44 (81.5%) were antigenically similar with ferret antisera raised against cell-propagated B/Colorado/06/2017-like V1A.1 reference virus. Ten (18.5%) reacted poorly (at titers that were 8-fold or greater reduced compared with the homologous virus titer) and belonged to clade V1A or genetic subclade V1A-3Del.
              • B/Yamagata: Phylogenetic analysis of 97 influenza B/Yamagata-lineage viruses indicate that the HA genes belonged to clade Y3. A total of 75 influenza B/Yamagata-lineage viruses were antigenically characterized, and all were antigenically similar to cell-propagated B/Phuket/3073/2013 (Y3), the reference vaccine virus representing the influenza B/Yamagata-lineage component of the 2018-19 Northern Hemisphere quadrivalent vaccines.
              Antiviral Resistance:

              Testing of influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses for resistance to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using next-generation sequencing analysis and/or a functional assay. Neuraminidase sequences of viruses are inspected to detect the presence of amino acid substitutions,previously associated with reduced or highly reduced inhibition by any of three neuraminidase inhibitors.In addition, a subset of viruses are tested using the neuraminidase inhibition assay with three neuraminidase inhibitors. The level of neuraminidase activity inhibition is reported using the thresholds recommended by the World Health Organization Expert Working Group of the Global Influenza Surveillance and Response System (GISRS)These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with an antiviral-resistant virus.
              Reporting of baloxavir susceptibility testing for the 2018-2019 influenza season will begin later this season. More information regarding influenza antiviral drug resistance can be found here.
              High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.
              Assessment of Virus Susceptibility to Neuraminidase Inhibitors Using Next-Generation Sequencing Analysis and/or Neuraminidase Inhibition Assay

              Oseltamivir Peramivir Zanamivir
              1,396 2 (0.1%) 2 (0.1%) 1,396 0 (0%) 2 (0.1%) 1,396 0 (0%) 0 (0%)
              755 2 (0.3%) 2 (0.3%) 755 0 (0%) 2 (0.3%) 755 0 (0%) 0 (0%)
              482 0 (0%) 0 (0%) 482 0 (0%) 0 (0%) 482 0 (0%) 0 (0%)
              64 0 (0%) 0 (0%) 64 0 (0%) 0 (0%) 64 0 (0%) 0 (0%)
              95 0 (0%) 0 (0%) 95 0 (0%) 0 (0%) 95 0 (0%) 0 (0%)
              Antiviral treatment as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at:http://www.cdc.gov/flu/antivirals/index.htm.



              Outpatient Illness Surveillance:

              Nationwide during week 9, 4.7% 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 2.2%.(ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
              On a regional level, the percentage of outpatient visits for ILI ranged from 3.3% to 9.3% during week 9. All 10 regions reported a percentage of outpatient visits for ILI at or above their region-specific baseline.
              Additional data on medically attended visits for ILI for current and past seasons and by geography (national, HHS region, or select states) are available on FluView Interactive http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

              View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation



              ILINet State Activity Indicator Map:

              Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below, or only slightly above, the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.
              The ILI Activity Indicator Map displays state-specific activity levels for multiple seasons and allows a visual representation of relative activity from state to state. More information is available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/main.html.
              During week 9, the following ILI activity levels were experienced:


              *This map uses the proportion of outpatient visits to health care providers for ILI to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
              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.
              Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map is based on reports from state and territorial epidemiologists. The data presented in this map are preliminary and may change as more data are received.
              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.


              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. Additional data displaying the influenza activity reported by state and territorial epidemiologists for the current and past seasons are available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/FluView8.html
              During week 9, the following influenza activity was reported:
                • 32 states (Alabama, Alaska, Arizona, Arkansas, Colorado, Connecticut, Georgia, Illinois, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Montana, Nevada, New Jersey, New Mexico, New York, North Carolina, North Dakota, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Utah, Virginia, West Virginia, and Wyoming) experienced high ILI activity.
                • Puerto Rico and seven states (California, Hawaii, Maine, Massachusetts, Nebraska, Washington, and Wisconsin) experienced moderate ILI activity.
                • New York City, the District of Columbia and eight states (Florida, Idaho, Michigan, Minnesota, New Hampshire, Ohio, South Dakota, and Vermont) experienced low ILI activity.
                • Three states (Delaware, Maryland, and Tennessee) experienced minimal ILI activity.
                • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.
                • Widespread influenza activity was reported by 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, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin and Wyoming).
                • Local influenza activity was reported by the District of Columbia and two states (Hawaii and Vermont).
                • Sporadic influenza activity was reported by the U.S. Virgin Islands.
                • Guam did not report.
                  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 10,567 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2018 and March 2, 2019. The overall hospitalization rate was 36.6 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 (107.7 per 100,000 population), followed by children aged 0-4 (49.3 per 100,000 population) and adults aged 50-64 (48.4 per 100,000 population). Among 10,567 hospitalizations, 10,076 (95.4%) were associated with influenza A virus, 404 (3.8%) with influenza B virus, 31 (0.3%) with influenza A virus and influenza B virus co-infection, and 56 (0.5%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,569 (66.0%) were A(H1N1)pdm09 virus and 810 (34.0%) were A(H3N2).
                  Among 1,621 hospitalized adults with information on underlying medical conditions, 1,471 (90.8%) had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, and obesity. Among 306 hospitalized children with information on underlying medical conditions, 138 (45.1%) had at least one underlying medical condition; the most commonly reported was asthma. Among 255 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 57 (22.4%) were pregnant.
                  Additional FluSurv-NET data displaying hospitalization rates for the current and past seasons and different age groups, as well as data on patient characteristics (such as influenza virus type, demographic, and clinical information), are available on FluView Interactive at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.
                  FluSurv-Net data is used to generate national estimates of the total numbers of flu cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available athttps://cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm.
                  Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
                  View Interactive Application | View Full Screen | View PowerPoint Presentation
                  FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancy percentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
                  View Interactive Application | View Full Screen | View PowerPoint Presentation

                  Pneumonia and Influenza (P&I) Mortality Surveillance:

                  Based on National Center for Health Statistics (NCHS) mortality surveillance data available on March 7, 2019, 7.5% of the deaths occurring during the week ending February 23, 2019 (week 8) were due to P&I. This percentage is above the epidemic threshold of 7.3% for week 8.
                  Additional pneumonia and influenza mortality data for current and past seasons and by geography (national, HHS region, or state) are available at on FluView Interactive http://gis.cdc.gov/grasp/fluview/mortality.html. Data displayed on the regional and state-level are aggregated by the state of residence of the decedent.

                  View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation

                  Influenza-Associated Pediatric Mortality:

                  Nine influenza-associated pediatric deaths were reported to CDC during week 9, eight of which occurred during the 2018-2019 influenza season. Four deaths were associated with an influenza A(H1N1)pdm09 virus and occurred during weeks 7, 8 and 9 (the weeks ending February 16, February 23 and March 2, 2019, respectively). One death was associated with an influenza A(H3) virus and occurred during week 9. Two deaths were associated with an influenza A virus for which no subtyping was performed and occurred during weeks 6 and 9 (the weeks ending February 9 and March 2, 2019). One death was associated with an influenza B virus and occurred during week 6.
                  A total of 64 influenza-associated pediatric deaths occurring during the 2018-2019 season have been reported to CDC.
                  An additional death that occurred during the 2015-2016 season was reported to CDC. This death was associated with an influenza A virus for which no subtyping was performed and brings the total number of reported influenza-associated deaths occurring during that season to 95.
                  Additional information on influenza-associated pediatric deaths including basic demographics, underlying conditions, bacterial co-infections, and place of death for the current and past seasons, is available on FluView Interactivehttp://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

                  View Interactive Application | View Full Screen | View PowerPoint Presentation


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

                  World Health Organization: Additional influenza surveillance information from participating WHO member nations is available throughFluNet 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 athttps://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.
                    --------------------------------------------------------------------------------
            https://www.cdc.gov/flu/weekly/index.htm
            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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            • #21
              2018-2019 Influenza Season Week 10 ending March 9, 2019

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

              Influenza activity decreased slightly, but remains elevated in the United States. Influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses continue to co-circulate. Below is a summary of the key influenza indicators for the week ending March 9, 2019:
              • Viral Surveillance:The percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories decreased slightly. Nationally, during week 10, influenza A(H3) viruses were reported more frequently than influenza A(H1N1)pdm09 viruses. During the most recent three weeks, influenza A(H3) viruses were reported more frequently than influenza A(H1N1)pdm09 viruses in HHS Regions 2, 4, 5, 6, 7, 8 and 10.
                • Virus Characterization:The majority of influenza viruses characterized antigenically are similar to the cell-grown reference viruses representing the 2018–2019 Northern Hemisphere influenza vaccine viruses.
                • Antiviral Resistance:The vast majority of influenza viruses tested (>99%) show susceptibility to oseltamivir and peramivir. All influenza viruses tested showed susceptibility to zanamivir.
              • Influenza-like Illness Surveillance:The proportion of outpatient visits for influenza-like illness (ILI) decreased slightly to 4.5%, which is above the national baseline of 2.2%. All 10 regions reported ILI at or above their region-specific baseline level.
                • ILI State Activity Indictor Map: 30 states experienced high ILI activity; 11 states experienced moderate ILI activity; New York City, the District of Columbia and five states experienced low ILI activity; Puerto Rico and four states experienced minimal ILI activity; and the U.S. Virgin Islands had insufficient data.
              • Geographic Spread of Influenza: The geographic spread of influenza in Puerto Rico and 46 states was reported as widespread; four states reported regional activity; the District of Columbia reported local activity; the U.S. Virgin Islands reported sporadic activity; and Guam did not report.
              • Influenza-associated Hospitalizations A cumulative rate of 41.3 laboratory-confirmed influenza-associated hospitalizations per 100,000 population was reported. The highest hospitalization rate is among adults 65 years and older (123.9 hospitalizations per 100,000 population).
              • Pneumonia and Influenza Mortality: The proportion of deaths attributed to pneumonia and influenza (P&I) was below the system-specific epidemic threshold in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
              • Influenza-associated Pediatric Deaths: Four influenza-associated pediatric deaths were reported to CDC during week 10.
              National and Regional Summary of Select Surveillance Components

              Elevated 51 of 54 25.8% Influenza A(H3)
              Elevated 6 of 6 20.4% Influenza A(H1N1)pdm09
              Elevated 3 of 4 24.3% Influenza A(H3)
              Elevated 5 of 6 26.7% Influenza A(H1N1)pdm09
              Elevated 8 of 8 16.1% Influenza A(H3)
              Elevated 6 of 6 29.2% Influenza A(H3)
              Elevated 5 of 5 29.1% Influenza A(H3)
              Elevated 4 of 4 29.9% Influenza A(H3)
              Elevated 6 of 6 34.0% Influenza A(H3)
              Elevated 4 of 5 13.0% Influenza A(H1N1)pdm09
              Elevated 4 of 4 32.2% Influenza A(H3)
              *https://www.hhs.gov/about/agencies/i...ces/index.html
              † Elevated means the % of visits for ILI is at or above the national or region-specific baseline
              § Includes all 50 states, the District of Columbia, Guam, Puerto Rico, and U.S. Virgin Islands

              U.S. Virologic Surveillance:

              WHO and NREVSS collaborating laboratories, which include both public health and clinical laboratories located in all 50 states, Puerto Rico, Guam, and the District of Columbia, report to CDC the total number of respiratory specimens tested for influenza and the number positive for influenza by virus type. In addition, public health laboratories also report the influenza A subtype (H1 or H3) and influenza B lineage information of the viruses they test and the age or age group of the persons from whom the specimens were collected.
              Additional virologic data, including national, regional and select state-level data, can be found at: http://gis.cdc.gov/grasp/fluview/flu...dashboard.html. Age group proportions and totals by influenza subtype reported by public health laboratories can be found at: http://gis.cdc.gov/grasp/fluview/flu_by_age_virus.html.
              The results of tests performed by clinical laboratories are summarized below.
              41,054 809,094
              10,591 (25.8%) 124,283 (15.4%)
              10,296 (97.2%) 119,654 (96.3%)
              295 (2.8%) 4,629 (3.7%)

              View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
              The results of tests performed by public health laboratories are summarized below.
              2,047 54,387
              1,345 27,552
              1,309 (97.3%) 26,818 (97.3%)
              478 (38.7%) 17,169 (67.2%)
              758 (61.3%) 6,725 (30.4%)
              73 1,267
              36 (2.7%) 734 (2.7%)
              4 (20.0%) 226 (48.0%)
              16 (80.0%) 245 (52.0%)
              16 263
              *The percent of specimens testing positive for influenza is not reported because public health laboratories often receive samples that have already tested positive for influenza at a clinical laboratory and therefore percent positive would not be a valid indicator of influenza activity. Additional information is available at http://www.cdc.gov/flu/weekly/overview.htm.


              View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation
              Influenza Virus Characterization:

              Close monitoring of influenza viruses is required to better assess the potential impact on public health. CDC characterizes influenza viruses through one or more tests including genomic sequencing, hemagglutination inhibition (HI) and/or neutralization based Focus Reduction assays (FRA). These data are used to compare how similar currently circulating influenza viruses are to the reference viruses used for developing new influenza vaccines and to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. Antigenic and genetic characterization of circulating influenza viruses gives an indication of the influenza vaccine's ability to induce an immune response against the wide array of influenza viruses that are co-circulating every season. However, annual vaccine effectiveness estimates are needed to determine how much protection was provided to the population by vaccination. On February 14, 2019, interim influenza effectiveness estimates for the 2018-2019 season were released and are available here.
              For nearly all influenza-positive surveillance samples received at CDC, next-generation sequencing is performed to determine the genetic identity of circulating influenza viruses and to monitor the evolutionary trajectory of viruses circulating in our population. Virus gene segments are classified into genetic clades/subclades based on phylogenetic analysis. However, genetic changes that classify the clades/subclades do not always result in antigenic changes. “Antigenic drift” is a term used to describe gradual antigenic change that occurs as viruses evolve changes to escape host immune pressure. 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 has antigenically or genetically characterized 1,467 influenza viruses collected September 30, 2018 – March 2, 2019, and submitted by U.S. laboratories, including 783 influenza A(H1N1)pdm09 viruses, 514 influenza A(H3N2) viruses, and 170 influenza B viruses.
              Influenza A Viruses
              Influenza B Viruses

              The majority of U.S. viruses submitted for characterization come from state and local public health laboratories. Due to Right Size Roadmapconsiderations, specimen submission guidance to laboratories is that, if available, 2 influenza A(H1N1)pdm09, 2 influenza A(H3N2), and 2 influenza B viruses be submitted every other week. Therefore, the numbers of each virus type/subtype characterized should be more balanced across subtypes/lineages but will not reflect the actual proportion of circulating viruses. In the figure below, the results of tests performed by public health labs are shown on the left and CDC sequence results (by genetic clade/subclade) are shown on the right.

              View Chart Data | View Full Screen | View PowerPoint Presentation
                • A (H1N1)pdm09: Phylogenetic analysis of the HA genes from 783 A(H1N1)pdm09 viruses showed that all belonged to clade 6B.1. Two hundred seventy six A(H1N1)pdm09 viruses were antigenically characterized, and 270 (97.8%) were antigenically similar (analyzed using HI with ferret antisera) to A/Michigan/45/2015 (6B.1), a cell-propagated A/Michigan/45/2015-like reference virus representing the A(H1N1)pdm09 component for the 2018-19 Northern Hemisphere influenza vaccines.
                • A (H3N2): Phylogenetic analysis of the HA genes from 514 A(H3N2) viruses revealed extensive genetic diversity with multiple clades/subclades co-circulating. The HA genes of circulating viruses belonged to clade 3C.2a (n=65), subclade 3C.2a1 (n=138) or clade 3C.3a (n=311). Two hundred twenty four A(H3N2) viruses were antigenically characterized by FRA with ferret antisera, and 138 (61.6%) A(H3N2) viruses tested were well-inhibited (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera raised against A/Singapore/INFIMH-16-0019/2016 (3C.2a1), a cell-propagated reference virus representing the A(H3N2) component of 2018-19 Northern Hemisphere influenza vaccines. Eighty-six (38.4%) viruses reacted poorly (at titers that were 8-fold or greater reduced compared with that of the homologous virus A/Singapore/INFIMH-16-0019/2016) and of those, 85 (98.8%) belonged to clade 3C.3a.
                • B/Victoria: Phylogenetic analysis of 73 B/Victoria-lineage viruses indicate that all HA genes belonged to genetic clade V1A, however genetic subclades which are antigenically distinct have emerged. Genetic subclades which are antigenically distinct include viruses with a two amino acid deletion (162-163) in the HA protein (V1A.1, previously abbreviated as V1A-2Del) and viruses with a three amino acid deletion (162-164) in the HA protein (abbreviated as V1A-3Del). Fifty-four B/Victoria lineage viruses were antigenically characterized and 44 (81.5%) were antigenically similar with ferret antisera raised against cell-propagated B/Colorado/06/2017-like V1A.1 reference virus. Ten (18.5%) reacted poorly (at titers that were 8-fold or greater reduced compared with the homologous virus titer) and belonged to clade V1A or genetic subclade V1A-3Del.
                • B/Yamagata: Phylogenetic analysis of 97 influenza B/Yamagata-lineage viruses indicate that the HA genes belonged to clade Y3. A total of 83 influenza B/Yamagata-lineage viruses were antigenically characterized, and all were antigenically similar to cell-propagated B/Phuket/3073/2013 (Y3), the reference vaccine virus representing the influenza B/Yamagata-lineage component of the 2018-19 Northern Hemisphere quadrivalent vaccines.
                Antiviral Resistance:

                Testing of influenza A(H1N1)pdm09, influenza A(H3N2), and influenza B viruses for resistance to the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) is performed at CDC using next-generation sequencing analysis and/or a functional assay. Neuraminidase sequences of viruses are inspected to detect the presence of amino acid substitutions,previously associated with reduced or highly reduced inhibition by any of three neuraminidase inhibitors.In addition, a subset of viruses are tested using the neuraminidase inhibition assay with three neuraminidase inhibitors. The level of neuraminidase activity inhibition is reported using the thresholds recommended by the World Health Organization Expert Working Group of the Global Influenza Surveillance and Response System (GISRS)These samples are routinely obtained for surveillance purposes rather than for diagnostic testing of patients suspected to be infected with an antiviral-resistant virus.
                Reporting of baloxavir susceptibility testing for the 2018-2019 influenza season will begin later this season. More information regarding influenza antiviral drug resistance can be found here.
                High levels of resistance to the adamantanes (amantadine and rimantadine) persist among influenza A(H1N1)pdm09 and influenza A(H3N2) viruses (the adamantanes are not effective against influenza B viruses). Therefore, data from adamantane resistance testing are not presented below.
                Assessment of Virus Susceptibility to Neuraminidase Inhibitors Using Next-Generation Sequencing Analysis and/or Neuraminidase Inhibition Assay

                Oseltamivir Peramivir Zanamivir
                1,477 2 (0.1%) 2 (0.1%) 1,477 0 (0%) 2 (0.1%) 1,477 0 (0%) 0 (0%)
                791 2 (0.3%) 2 (0.3%) 791 0 (0%) 2 (0.3%) 791 0 (0%) 0 (0%)
                519 0 (0%) 0 (0%) 519 0 (0%) 0 (0%) 519 0 (0%) 0 (0%)
                71 0 (0%) 0 (0%) 71 0 (0%) 0 (0%) 71 0 (0%) 0 (0%)
                96 0 (0%) 0 (0%) 96 0 (0%) 0 (0%) 96 0 (0%) 0 (0%)
                Antiviral treatment as early as possible is recommended for patients with confirmed or suspected influenza who have severe, complicated, or progressive illness; who require hospitalization; or who are at high risk for serious influenza-related complications. Additional information on recommendations for treatment and chemoprophylaxis of influenza virus infection with antiviral agents is available at:http://www.cdc.gov/flu/antivirals/index.htm.



                Outpatient Illness Surveillance:

                Nationwide during week 10, 4.5% 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 2.2%.(ILI is defined as fever (temperature of 100°F [37.8°C] or greater) and cough and/or sore throat.)
                On a regional level, the percentage of outpatient visits for ILI ranged from 3.0% to 8.5% during week 10. All 10 regions reported a percentage of outpatient visits for ILI at or above their region-specific baseline.
                Additional data on medically attended visits for ILI for current and past seasons and by geography (national, HHS region, or select states) are available on FluView Interactive http://gis.cdc.gov/grasp/fluview/flu...dashboard.html.

                View National and Regional Level Graphs and Data | View Chart Data | View Full Screen | View PowerPoint Presentation



                ILINet State Activity Indicator Map:

                Data collected in ILINet are used to produce a measure of ILI activity* by state. Activity levels are based on the percent of outpatient visits in a state due to ILI and are compared to the average percent of ILI visits that occur during weeks with little or no influenza virus circulation. Activity levels range from minimal, which would correspond to ILI activity from outpatient clinics being below, or only slightly above, the average, to high, which would correspond to ILI activity from outpatient clinics being much higher than average.
                The ILI Activity Indicator Map displays state-specific activity levels for multiple seasons and allows a visual representation of relative activity from state to state. More information is available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/main.html.
                During week 10, the following ILI activity levels were experienced:


                *This map uses the proportion of outpatient visits to health care providers for ILI to measure the ILI activity level within a state. It does not, however, measure the extent of geographic spread of flu within a state. Therefore, outbreaks occurring in a single city could cause the state to display high activity levels.
                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.
                Data displayed in this map are based on data collected in ILINet, whereas the State and Territorial flu activity map is based on reports from state and territorial epidemiologists. The data presented in this map are preliminary and may change as more data are received.
                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.


                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. Additional data displaying the influenza activity reported by state and territorial epidemiologists for the current and past seasons are available on FluView Interactive at https://gis.cdc.gov/grasp/fluview/FluView8.html
                During week 10, the following influenza activity was reported:
                  • 30 states (Alabama, Alaska, Arkansas, Colorado, Connecticut, Georgia, Indiana, Iowa, Kansas, Kentucky, Louisiana, Mississippi, Missouri, Nebraska, New Jersey, New Mexico, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, Texas, Utah, Virginia, Washington, Wisconsin and Wyoming) experienced high ILI activity.
                  • 11 states (California, Hawaii, Illinois, Maine, Maryland, Montana, Nevada, New York, South Dakota, Vermont and West Virginia) experienced moderate ILI activity.
                  • New York City, the District of Columbia and five states (Idaho, Massachusetts, Michigan, Minnesota and New Hampshire) experienced low ILI activity.
                  • Puerto Rico and four states (Arizona, Delaware, Florida and Tennessee) experienced minimal ILI activity.
                  • Data were insufficient to calculate an ILI activity level from the U.S. Virgin Islands.
                  • Widespread influenza activity was reported by Puerto Rico and 46 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, Utah, Virginia, Washington, West Virginia, Wisconsin and Wyoming).
                  • Regional influenza activity was reported by four states (Hawaii, Tennessee, Texas and Vermont).
                  • Local influenza activity was reported by the District of Columbia.
                  • Sporadic influenza activity was reported by the U.S. Virgin Islands.
                  • Guam did not report.
                    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 11,922 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2018 and March 9, 2019. The overall hospitalization rate was 41.3 per 100,000 population. The highest rate of hospitalization was among adults aged ≥65 (123.9 per 100,000 population), followed by children aged 0-4 (54.8 per 100,000 population) and adults aged 50-64 (54.0 per 100,000 population). Among 11,922 hospitalizations, 11,395 (95.6%) were associated with influenza A virus, 429 (3.6%) with influenza B virus, 34 (0.3%) with influenza A virus and influenza B virus co-infection, and 64 (0.5%) with influenza virus for which the type was not determined. Among those with influenza A subtype information, 1,727 (63.6%) were A(H1N1)pdm09 virus and 986 (36.3%) were A(H3N2).
                    Among 1,791 hospitalized adults with information on underlying medical conditions, 1,616 (90.2%) had at least one reported underlying medical condition, the most commonly reported were cardiovascular disease, metabolic disorder, and obesity. Among 320 hospitalized children with information on underlying medical conditions, 146 (45.6%) had at least one underlying medical condition; the most commonly reported was asthma. Among 274 hospitalized women of childbearing age (15-44 years) with information on pregnancy status, 64 (23.4%) were pregnant.
                    Additional FluSurv-NET data displaying hospitalization rates for the current and past seasons and different age groups, as well as data on patient characteristics (such as influenza virus type, demographic, and clinical information), are available on FluView Interactive at: http://gis.cdc.gov/GRASP/Fluview/FluHospRates.html and http://gis.cdc.gov/grasp/fluview/FluHospChars.html.
                    FluSurv-Net data is used to generate national estimates of the total numbers of flu cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available athttps://cdc.gov/flu/about/burden/preliminary-in-season-estimates.htm.
                    Data from the Influenza Hospitalization Surveillance Network (FluSurv-NET), a population-based surveillance for influenza related hospitalizations in children and adults in 13 U.S. states. Cumulative incidence rates are calculated using the National Center for Health Statistics’ (NCHS) population estimates for the counties included in the surveillance catchment area.
                    View Interactive Application | View Full Screen | View PowerPoint Presentation
                    FluSurv-NET data are preliminary and displayed as they become available. Therefore, figures are based on varying denominators as some variables represent information that may require more time to be collected. Data are refreshed and updated weekly. Asthma includes a medical diagnosis of asthma or reactive airway disease; Cardiovascular diseases include conditions such as coronary heart disease, cardiac valve disorders, congestive heart failure, and pulmonary hypertension; does not include isolated hypertension; Chronic lung diseases include conditions such as chronic obstructive pulmonary disease, bronchiolitis obliterans, chronic aspiration pneumonia, and interstitial lung disease; Immune suppression includes conditions such as immunoglobulin deficiency, leukemia, lymphoma, HIV/AIDS, and individuals taking immunosuppressive medications; Metabolic disorders include conditions such as diabetes mellitus; Neurologic diseases include conditions such as seizure disorders, cerebral palsy, and cognitive dysfunction; Neuromuscular diseases include conditions such as multiple sclerosis and muscular dystrophy; Obesity was assigned if indicated in patient's medical chart or if body mass index (BMI) >30 kg/m2; Pregnancy percentage calculated using number of female cases aged between 15 and 44 years of age as the denominator; Renal diseases include conditions such as acute or chronic renal failure, nephrotic syndrome, glomerulonephritis, and impaired creatinine clearance; No known condition indicates that the case did not have any known high risk medical condition indicated in medical chart at the time of hospitalization.
                    View Interactive Application | View Full Screen | View PowerPoint Presentation

                    Pneumonia and Influenza (P&I) Mortality Surveillance:

                    Based on National Center for Health Statistics (NCHS) mortality surveillance data available on March 14, 2019, 7.2% of the deaths occurring during the week ending March 2, 2019 (week 9) were due to P&I. This percentage is below the epidemic threshold of 7.3% for week 9.
                    Additional pneumonia and influenza mortality data for current and past seasons and by geography (national, HHS region, or state) are available at on FluView Interactive http://gis.cdc.gov/grasp/fluview/mortality.html. Data displayed on the regional and state-level are aggregated by the state of residence of the decedent.

                    View Regional and State Level Data | View Chart Data | View Full Screen | View PowerPoint Presentation

                    Influenza-Associated Pediatric Mortality:

                    Four influenza-associated pediatric deaths were reported to CDC during week 10. One death was associated with an influenza A(H1N1)pdm09 virus and occurred during week 6 (the week ending February 9, 2019). Two deaths were associated with an influenza A(H3) virus and occurred during weeks 9 and 10 (the weeks ending March 2 and March 9, 2019, respectively). One death was associated with an influenza A virus for which no subtyping was performed and occurred during week 9 (the week ending March 2, 2019).
                    A total of 68 influenza-associated pediatric deaths occurring during the 2018-2019 season have been reported to CDC.
                    Additional information on influenza-associated pediatric deaths including basic demographics, underlying conditions, bacterial co-infections, and place of death for the current and past seasons, is available on FluView Interactivehttp://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html.

                    View Interactive Application | View Full Screen | View PowerPoint Presentation


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

                    World Health Organization: Additional influenza surveillance information from participating WHO member nations is available throughFluNet 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 athttps://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.
                      --------------------------------------------------------------------------------
              https://www.cdc.gov/flu/weekly/index.htm
              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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