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  • #46
    Weekly U.S. Influenza Surveillance Report


    Updated May 20, 2022

    Note: CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review.

    Key Updates for Week 19, ending May 14, 2022

    Seasonal influenza viruses continue to circulate and activity is increasing in parts of the country.
    Viruses


    Clinical Lab7.0%


    positive for influenza
    this week


    Public Health Lab
    The majority of viruses
    detected are influenza A(H3N2).


    Virus Characterization
    Genetic and antigenic characterization and antiviral susceptibility are summarized in this report.
    Illness

    Outpatient Respiratory Illness2.4%


    of visits to a health care provider are for respiratory illness this week
    (below baseline)


    Outpatient Respiratory Illness: Activity Map
    This week, 7 jurisdictions experienced moderate activity and 3 jurisdictions experienced high or very high activity.

    Long-term Care Facilities0.7%


    of facilities reported
    ≥ 1 influenza-positive test
    among residents this week.

    Severe Disease


    FluSurv-NET14.4 per 100,000


    cumulative hospitalization rate

    HHS Protect Hospitalizations3,153


    patients admitted to hospitals with influenza
    this week.


    NCHS Mortality7.5 %


    of deaths attributed to pneumonia, influenza, or COVID-19 this week (above threshold)

    Pediatric Deaths0


    influenza-associated deaths reported this week with a total of 24 so far this season

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

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

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

    Key Points
    • Seasonal influenza viruses continue to circulate, and activity is increasing in parts of the country.
    • The majority of influenza viruses detected are A(H3N2). H3N2 viruses identified so far this season are genetically closely related to the vaccine virus. Antigenic data show that the majority of the H3N2 viruses characterized are antigenically different from the vaccine reference viruses. While the number of B/Victoria viruses circulating this season is small, the majority of the B/Victoria viruses characterized are antigenically similar to the vaccine reference virus.
    • The percentage of outpatient visits due to respiratory illness remained stable (change of ≤ 0.1%) compared to last week and, while trending upward, remains below baseline. Influenza is contributing to levels of respiratory illness, but other respiratory viruses are also circulating. The relative contribution of influenza varies by location.
    • The number of hospital admissions with laboratory confirmed influenza that were reported to HHS Protect increased slightly compared with the previous week.
    • Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). As of MMWR week 19, the overall cumulative hospitalization rate was 14.4 per 100,000 population, and the overall weekly hospitalization rate was 0.6 per 100,000 population. Reporting of recent hospital admissions can be subject to reporting delays; therefore, as hospitalization data are received each week, prior rates are updated accordingly.
    • No influenza-associated pediatric deaths were reported this week. There have been 24 pediatric deaths reported this season.
    • CDC estimates that, so far this season, there have been at least 6.7 million flu illnesses, 69,000 hospitalizations, and 4,200 deaths from flu.
    • An annual flu vaccine is the best way to protect against flu. Vaccination can prevent serious outcomes in people who get vaccinated but still get sick. CDC continues to recommend that everyone ages 6 months and older get a flu vaccine as long as flu activity continues.
    • There are also prescription flu antiviral drugs that can be used to treat flu illness.
    U.S. Virologic Surveillance


    Nationally, the percentage of specimens testing positive for influenza in clinical laboratories decreased. However, activity varied by region; percent positivity increased by more than 0.1 percentage point this week in Regions 1 and 4, and was similar to or lower than the previous week in all other regions. Influenza A(H3N2) viruses have been the most frequently detected influenza viruses this season. Of the 11,681 influenza positives reported this season by the public health labs and also tested for SARS-CoV-2, 531 (4.5%) were also positive for SARS-CoV-2. For regional and state level data and age group distribution, please visit FluView Interactive. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
    Clinical Laboratories


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

    No. of specimens tested 62,961 2,448,486
    No. of positive specimens (%) 4,418 (7.0%) 106,034 (4.3%)
    Positive specimens by type
    Influenza A 4,364 (98.8%) 104,411 (98.5%)
    Influenza B 54 (1.2%) 1,623 (1.5%)

    View Chart Data | View Full Screen Public Health Laboratories


    The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
    No. of specimens tested 12,966 811,756
    No. of positive specimens 436 21,254
    Positive specimens by type/subtype
    Influenza A 433 (99.3%) 21,134 (99.4%)
    (H1N1)pdm09 1 (0.4%) 18 (0.1%)
    H3N2 255 (99.6%) 16,362 (99.9%)
    H3N2v 0 1 (<0.1%)
    Subtyping not performed 177 4,753
    Influenza B 3 (0.7%) 120 (0.6%)
    Yamagata lineage 0 1 (2.6%)
    Victoria lineage 0 38 (97.4%)
    Lineage not performed 3 81



    View Chart Data | View Full Screen

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


    CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local public health laboratories using the Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of circulating influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir.

    CDC has genetically characterized 1,379 influenza viruses collected since October 3, 2021. H3N2 viruses identified so far this season are genetically closely related to the vaccine virus, but there are some antigenic differences that have developed as H3N2 viruses have continued to evolve.
    A/H1 5
    6B.1A 5 (100%) 5a.1 3 (60%)
    5a.2 2 (40%)
    A/H3 1,351
    3C.2a1b 1,351 (100%) 1a 3 (0.2%)
    1b 1 (0.1%)
    2a 0
    2a.1 0
    2a.2 1,347 (99.7%)
    3C.3a 0 3a 0
    B/Victoria 23
    V1A 23 (100%) V1A 0
    V1A.1 0
    V1A.3 9 (39.1%)
    V1A.3a 0
    V1A.3a.1 0
    V1A.3a.2 14 (60.9%)
    B/Yamagata 0
    Y3 0
    CDC antigenically characterizes influenza viruses by hemagglutination inhibition (HI) (H1N1pdm09, B/Victoria and B/Yamagata viruses) or neutralization-based HINT (H3N2 viruses) using antisera that ferrets make after being infected with reference viruses representing the 2021-2022 Northern Hemisphere recommended egg-based and cell or recombinant-based vaccine viruses. Antigenic differences between viruses are determined by comparing how well the antibodies made against the vaccine reference viruses recognize the circulating viruses that have been grown in cell culture. Ferret antisera are useful because antibodies raised against a particular virus can often recognize small changes in the surface proteins of other viruses. In HI assays, viruses with similar antigenic properties have antibody titer differences of less than or equal to 4-fold when compared to the reference (vaccine) virus. In HINT, viruses with similar antigenic properties have antibody neutralization titer differences of less than 8-fold. Viruses selected for antigenic characterization are a subset representing the genetic changes in the surface proteins seen in genetically characterized viruses.

    Influenza A Viruses
    • A (H1N1)pdm09: Three A(H1N1)pdm09 viruses were antigenically characterized by HI, and 2 (67%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown A/Wisconsin/588/2019-like reference viruses representing the A(H1N1)pdm09 component for the cell- and recombinant-based influenza vaccines, and 2 (67%) were well recognized by ferret antisera to egg-grown A/Victoria/2570/2019-like reference viruses representing the A(H1N1)pdm09 component for the egg-based influenza vaccines.
    • A (H3N2): A subset of 101 A(H3N2) viruses were antigenically characterized by HINT, and 4 (4%) were well recognized (reacting at titers that were within 8-fold of the homologous virus titer) by ferret antisera to cell-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for the cell- and recombinant-based influenza vaccines, and 19 (19%) were well recognized by ferret antisera to egg-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for egg-based influenza vaccines.

    Influenza B Viruses
    • B/Victoria: Fifteen B/Victoria lineage viruses were antigenically characterized by HI, and 11 (73%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for the cell- and recombinant-based influenza vaccines, and 11 (73%) were well recognized by ferret antisera to egg-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for egg-based influenza vaccines.
    • B/Yamagata: No influenza B/Yamagata-lineage viruses were available for antigenic characterization.

    Assessment of Virus Susceptibility to Antiviral Medications

    CDC assesses susceptibility of influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Information about antiviral susceptibility test methods can be found at U.S. Influenza Surveillance: Purpose and Methods | CDC.

    Viruses collected in the United States since October 3, 2021, were tested for antiviral susceptibility as follows:
    Neuraminidase
    Inhibitors
    Oseltamivir Viruses
    Tested
    1,389 5 1,361 23 0
    Reduced
    Inhibition
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    Highly
    Reduced
    Inhibition
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    Peramivir Viruses
    Tested
    1,389 5 1,361 23 0
    Reduced
    Inhibition
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    Highly
    Reduced
    Inhibition
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    Zanamivir Viruses
    Tested
    1,389 5 1,361 23 0
    Reduced
    Inhibition
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    Highly
    Reduced
    Inhibition
    (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
    PA Cap-Dependent Endonuclease Inhibitor Baloxavir Viruses
    Tested
    1,361 5 1,340 23 0
    Reduced
    Susceptibility
    1 (0.1%) (0.0%) 1 (0.1%) (0.0%) (0.0%)

    One A(H3N2) virus had a PA-I38M amino acid substitution previously associated with reduced baloxavir susceptibility and showed ~8-fold reduced susceptibility to baloxavir in vitro.

    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, use of these antivirals for treatment and prevention of influenza A virus infection is not recommended, and data from adamantane resistance testing are not presented.
    Outpatient Respiratory Illness Surveillance


    The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
    Outpatient Respiratory Illness Visits


    Nationwide during week 19, 2.4% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. This remained stable (change of ≤ 0.1%) compared to week 18 but has been trending upward since early March. Seven of the 10 HHS Regions are below their region-specific baselines; Regions 1, 2, and 10 are above their respective baselines. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



    * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


    View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


    More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

    The percentage of visits for respiratory illness reported in ILINet is trending upward in all age groups (0-4 years, 5-24 years, 25-49 years, 50-64 years, and 65+ years).



    * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

    View Chart Data | View Full Screen
    Outpatient Respiratory Illness Activity Map


    Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
    Week 19
    (Week ending
    May 14, 2022)
    Week 18
    (Week ending
    May 7, 2022)
    Week 19
    (Week ending
    May 14, 2022)
    Week 18
    (Week ending
    May 7, 2022)
    Very High 0 1 1 3
    High 3 4 18 14
    Moderate 7 3 36 36
    Low 7 9 92 82
    Minimal 36 38 494 513
    Insufficient Data 2 0 288 281



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

    Additional information about medically attended visits for ILI for current and past seasons:
    Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
    Long-term Care Facility (LTCF) Surveillance


    LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 19, 99 (0.7%) of 14,113 reporting LTCFs reported at least one influenza positive test among their residents.



    View Chart Dataexcel icon | View Full Screen

    Additional information about long-term care facility surveillance:
    Surveillance Methods | Additional Dataexternal icon
    Hospitalization Surveillance

    FluSurv-NET


    The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. As data are received each week, prior case counts and rates are updated accordingly.

    Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). For this reason, comparisons between cumulative end of season rates for prior seasons and cumulative hospitalization rates beyond week 17 of the 2021-2022 season should be interpreted with caution. Comparisons with similar late-season weekly rates is not possible since data from similar weeks in prior seasons is not available. A graph showing weekly rates for the 2021-2022 season beyond week 17 has been added to FluView.

    A total of 4,225 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2021, and May 14, 2022. As of MMWR week 19, the overall cumulative hospitalization rate was 14.4 per 100,000 population and the overall weekly hospitalization rate was 0.6 per 100,000 population. The weekly rate for the 2021-22 season during MMWR week 17 (1.1) was the highest weekly rate observed during that week since the 2010-2011 season. While the cumulative hospitalization rate for the 2021-22 season is lower than the end of-season rates observed during the 4 seasons preceding the COVID-19 pandemic (these ranged from 62.0 to 102.9 per 100,000 during the 2016-17 through 2019-20 seasons), additional data (“backfill”) may change that rate subsequent to this report.

    When examining rates by age, the highest rate of hospitalization per 100,000 population was among adults aged 65 and older (41.7). Among adults aged 65 and older, rates were highest among adults aged 85 and older (83.7). Among persons aged less than 65 years, hospitalization rates per 100,000 population were highest among children aged 0-4 years (18), followed by adults aged 50-64 years (13.4). When examining rates by race and ethnicity, the highest rate of hospitalization per 100,000 population was among non-Hispanic American Indian or Alaska Native persons (23.6), followed by non-Hispanic Black persons (16.7).

    Among 4,225 hospitalizations, 4,087 (96.7%) were associated with influenza A virus, 125 (3%) with influenza B virus, 5 (0.1%) with influenza A virus and influenza B virus co-infection, and 8 (0.2%) with influenza virus for which the type was not determined. Among 960 hospitalizations with influenza A subtype information, 951 (99.1%) were A(H3N2), and 9 (0.9%) were A(H1N1)pdm09. Based on preliminary data, of the 4,225 laboratory-confirmed influenza-associated hospitalizations, 2.4% also tested positive for SARS-CoV-2.

    Among 1848 hospitalized adults with information on underlying medical conditions, 93.8% had at least one reported underlying medical condition the most commonly reported were hypertension, cardiovascular disease, metabolic disorder, and obesity. Among 291 hospitalized children with information on underlying medical conditions, 67.7% had at least one reported underlying medical condition; the most commonly reported condition was asthma.

    FluSurv-Net data are used to generate national estimates of the total numbers of influenza cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available at https://www.cdc.gov/flu/about/burden...-estimates.htm



    View Full Screen

    Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
    Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics

    FluSurv-Net data are used to generate national estimates of the total numbers of influenza cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available at https://www.cdc.gov/flu/about/burden...-estimates.htm
    HHS Protect Hospitalization Surveillance


    Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 19, 3,153 patients with laboratory-confirmed influenza were admitted to the hospital.

    Effective February 2, 2022, hospitals are required to report laboratory-confirmed influenza hospitalizations to HHS Protect daily. Prior to this update, reporting influenza hospitalizations was optional. See COVID-19 Guidance for Hospital Reporting and FAQspdf iconexternal icon for additional details on this guidance.



    View Chart Dataexcel icon | View Full Screen

    Additional HHS Protect hospitalization surveillance information:
    Surveillance Methods | Additional Dataexternal icon
    Mortality Surveillance

    National Center for Health Statistics (NCHS) Mortality Surveillance


    Based on NCHS mortality surveillance data available on May 19, 2022, 7.5% of the deaths that occurred during the week ending May 14, 2022 (week 19), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 6.5% for this week. Among the 1,409 PIC deaths reported for this week, 592 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and 27 listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



    View Chart Dataexcel icon | View Full Screen

    Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
    Surveillance Methods | FluView Interactive
    Influenza-Associated Pediatric Mortality


    No influenza-associated pediatric deaths were reported to CDC during week 19.

    A total of 24 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


    View Full Screen

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


    Additional National and International Influenza Surveillance Information


    FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

    National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

    U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
    Additional influenza surveillance information from participating WHO member nations is available through
    FluNetexternal icon and the Global Epidemiology Reports.external icon

    WHO Collaborating Centers for Influenza:
    Australiaexternal icon, Chinaexternal icon, Japanexternal icon, the United Kingdomexternal icon, and the United States (CDC in Atlanta, Georgia)

    Europe:
    The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Controlexternal icon.

    Public Health Agency of Canada:
    The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch reportexternal icon.

    Public Health England:
    The most up-to-date influenza information from the United Kingdom is available from Public Health Englandexternal icon.

    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.

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

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    • #47
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      • #48

        Weekly U.S. Influenza Surveillance Report


        Updated May 27, 2022

        Note: CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review.

        Key Updates for Week 20, ending May 21, 2022

        Seasonal influenza viruses continue to circulate, and activity is increasing in parts of the country.
        Viruses


        Clinical Lab6.4%


        positive for influenza
        this week


        Public Health Lab
        The majority of viruses
        detected are influenza A(H3N2).


        Virus Characterization
        Genetic and antigenic characterization and antiviral susceptibility are summarized in this report.
        Illness

        Outpatient Respiratory Illness2.4%


        of visits to a health care provider are for respiratory illness this week
        (below baseline)


        Outpatient Respiratory Illness: Activity Map
        This week, 6 jurisdictions experienced moderate activity and 2 jurisdictions experienced high or very high activity.

        Long-term Care Facilities0.6%


        of facilities reported
        ≥ 1 influenza-positive test
        among residents this week.

        Severe Disease


        FluSurv-NET15.5 per 100,000


        cumulative hospitalization rate

        HHS Protect Hospitalizations3,039


        patients admitted to hospitals with influenza
        this week.


        NCHS Mortality8.0 %


        of deaths attributed to pneumonia, influenza, or COVID-19 this week (above threshold)

        Pediatric Deaths1


        influenza-associated death reported this week for a total of 25 so far this season

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

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

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

        Key Points
        • Seasonal influenza viruses continue to circulate, and activity is increasing in parts of the country.
        • The majority of influenza viruses detected are A(H3N2). H3N2 viruses identified so far this season are genetically closely related to the vaccine virus. Antigenic data show that the majority of the H3N2 viruses characterized are antigenically different from the vaccine reference viruses. While the number of B/Victoria viruses circulating this season is small, the majority of the B/Victoria viruses characterized are antigenically similar to the vaccine reference virus.
        • The percentage of outpatient visits due to respiratory illness remained stable (change of ≤ 0.1%) compared to last week. Influenza is contributing to levels of respiratory illness, but other respiratory viruses are also circulating. The relative contribution of influenza varies by location.
        • The numbers of hospital admissions with laboratory confirmed influenza that were reported to HHS Protect have remained approximately stable over the past four weeks.
        • Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). As of MMWR week 20, the overall cumulative hospitalization rate was 15.5 per 100,000 population, and the overall weekly hospitalization rate was 0.6 per 100,000 population. Reporting of recent hospital admissions can be subject to reporting delays; therefore, as hospitalization data are received each week, prior rates are updated accordingly.
        • One influenza-associated pediatric death was reported this week. There have been 25 pediatric deaths reported this season.
        • CDC estimates that, so far this season, there have been at least 7.3 million flu illnesses, 74,000 hospitalizations, and 4,500 deaths from flu.
        • An annual flu vaccine is the best way to protect against flu. Vaccination can prevent serious outcomes in people who get vaccinated but still get sick. CDC continues to recommend that everyone ages 6 months and older get a flu vaccine as long as flu activity continues.
        • There are also prescription flu antiviral drugs that can be used to treat flu illness.
        U.S. Virologic Surveillance


        Nationally, the percentage of specimens testing positive for influenza in clinical laboratories decreased. However, activity varied by region; percent positivity increased by more than 0.1 percentage point this week in regions 4 and 9, and was similar to or lower than the previous week in all other regions. Influenza A(H3N2) viruses have been the most frequently detected influenza viruses this season. Of the 12,077 influenza positives reported this season by the public health labs and also tested for SARS-CoV-2, 540 (4.5%) were also positive for SARS-CoV-2. For regional and state level data and age group distribution, please visit FluView Interactive. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
        Clinical Laboratories


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

        No. of specimens tested 65,734 2,532,110
        No. of positive specimens (%) 4,225 (6.4%) 111,760 (4.4%)
        Positive specimens by type
        Influenza A 4,210 (99.6%) 110,114 (98.5%)
        Influenza B 15 (0.4%) 1,646 (1.5%)

        View Chart Data | View Full Screen Public Health Laboratories


        The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
        No. of specimens tested 13,124 827,290
        No. of positive specimens 361 22,013
        Positive specimens by type/subtype
        Influenza A 361 (100%) 21,893 (99.5%)
        (H1N1)pdm09 3 (1.6%) 21 (0.1%)
        H3N2 188 (98.4%) 16,973 (99.9%)
        H3N2v 0 1 (<0.1%)
        Subtyping not performed 170 4,898
        Influenza B 0 (0%) 120 (0.5%)
        Yamagata lineage 0 1 (2.6%)
        Victoria lineage 0 38 (97.4%)
        Lineage not performed 0 81



        View Chart Data | View Full Screen

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


        CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local public health laboratories using the Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of circulating influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir.

        CDC has genetically characterized 1,401 influenza viruses collected since October 3, 2021. H3N2 viruses identified so far this season are genetically closely related to the vaccine virus, but there are some antigenic differences that have developed as H3N2 viruses have continued to evolve.
        A/H1 5
        6B.1A 5 (100%) 5a.1 3 (60%)
        5a.2 2 (40%)
        A/H3 1,372
        3C.2a1b 1,372 (100%) 1a 3 (0.2%)
        1b 1 (0.1%)
        2a 0
        2a.1 0
        2a.2 1,368 (99.7%)
        3C.3a 0 3a 0
        B/Victoria 24
        V1A 24 (100%) V1A 0
        V1A.1 0
        V1A.3 9 (37.5%)
        V1A.3a 0
        V1A.3a.1 0
        V1A.3a.2 15 (62.5%)
        B/Yamagata 0
        Y3 0
        CDC antigenically characterizes influenza viruses by hemagglutination inhibition (HI) (H1N1pdm09, B/Victoria and B/Yamagata viruses) or neutralization-based HINT (H3N2 viruses) using antisera that ferrets make after being infected with reference viruses representing the 2021-2022 Northern Hemisphere recommended egg-based and cell or recombinant-based vaccine viruses. Antigenic differences between viruses are determined by comparing how well the antibodies made against the vaccine reference viruses recognize the circulating viruses that have been grown in cell culture. Ferret antisera are useful because antibodies raised against a particular virus can often recognize small changes in the surface proteins of other viruses. In HI assays, viruses with similar antigenic properties have antibody titer differences of less than or equal to 4-fold when compared to the reference (vaccine) virus. In HINT, viruses with similar antigenic properties have antibody neutralization titer differences of less than 8-fold. Viruses selected for antigenic characterization are a subset representing the genetic changes in the surface proteins seen in genetically characterized viruses.

        Influenza A Viruses
        • A (H1N1)pdm09: Three A(H1N1)pdm09 viruses were antigenically characterized by HI, and 2 (67%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown A/Wisconsin/588/2019-like reference viruses representing the A(H1N1)pdm09 component for the cell- and recombinant-based influenza vaccines, and 2 (67%) were well recognized by ferret antisera to egg-grown A/Victoria/2570/2019-like reference viruses representing the A(H1N1)pdm09 component for the egg-based influenza vaccines.
        • A (H3N2): A subset of 108 A(H3N2) viruses were antigenically characterized by HINT, and 4 (4%) were well recognized (reacting at titers that were within 8-fold of the homologous virus titer) by ferret antisera to cell-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for the cell- and recombinant-based influenza vaccines, and 19 (18%) were well recognized by ferret antisera to egg-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for egg-based influenza vaccines.

        Influenza B Viruses
        • B/Victoria: Fifteen B/Victoria lineage viruses were antigenically characterized by HI, and 11 (73%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for the cell- and recombinant-based influenza vaccines, and 11 (73%) were well recognized by ferret antisera to egg-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for egg-based influenza vaccines.
        • B/Yamagata: No influenza B/Yamagata-lineage viruses were available for antigenic characterization.

        Assessment of Virus Susceptibility to Antiviral Medications

        CDC assesses susceptibility of influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Information about antiviral susceptibility test methods can be found at U.S. Influenza Surveillance: Purpose and Methods | CDC.

        Viruses collected in the United States since October 3, 2021, were tested for antiviral susceptibility as follows:
        Neuraminidase
        Inhibitors
        Oseltamivir Viruses
        Tested
        1,417 5 1,388 24 0
        Reduced
        Inhibition
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        Highly
        Reduced
        Inhibition
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        Peramivir Viruses
        Tested
        1,417 5 1,388 24 0
        Reduced
        Inhibition
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        Highly
        Reduced
        Inhibition
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        Zanamivir Viruses
        Tested
        1,417 5 1,388 24 0
        Reduced
        Inhibition
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        Highly
        Reduced
        Inhibition
        (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
        PA Cap-Dependent Endonuclease Inhibitor Baloxavir Viruses
        Tested
        1,396 5 1,367 24 0
        Reduced
        Susceptibility
        1 (0.1%) (0.0%) 1 (0.1%) (0.0%) (0.0%)

        One A(H3N2) virus had a PA-I38M amino acid substitution previously associated with reduced baloxavir susceptibility and showed ~8-fold reduced susceptibility to baloxavir in vitro.

        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, use of these antivirals for treatment and prevention of influenza A virus infection is not recommended, and data from adamantane resistance testing are not presented.
        Outpatient Respiratory Illness Surveillance


        The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
        Outpatient Respiratory Illness Visits


        Nationwide during week 20, 2.4% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. This remained stable (change of ≤ 0.1%) compared to week 19. Six of the 10 HHS Regions are below their region-specific baselines; regions 1, 2, and 10 are above their respective baselines, while Region 4 is at its baseline. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



        * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


        View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


        More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

        The percentage of visits for respiratory illness reported in ILINet is trending upward in all age groups (0-4 years, 5-24 years, 25-49 years, 50-64 years, and 65+ years).



        * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

        View Chart Data | View Full Screen
        Outpatient Respiratory Illness Activity Map


        Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
        Week 20
        (Week ending
        May 21, 2022)
        Week 19
        (Week ending
        May 14, 2022)
        Week 20
        (Week ending
        May 21, 2022)
        Week 19
        (Week ending
        May 14, 2022)
        Very High 0 0 4 3
        High 2 5 17 18
        Moderate 6 5 28 38
        Low 10 10 90 94
        Minimal 36 35 512 505
        Insufficient Data 1 0 278 271



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

        Additional information about medically attended visits for ILI for current and past seasons:
        Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
        Long-term Care Facility (LTCF) Surveillance


        LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 20, 89 (0.6%) of 14,189 reporting LTCFs reported at least one influenza positive test among their residents.



        View Chart Dataexcel icon | View Full Screen

        Additional information about long-term care facility surveillance:
        Surveillance Methods | Additional Dataexternal icon
        Hospitalization Surveillance

        FluSurv-NET


        The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. As data are received each week, prior case counts and rates are updated accordingly.

        Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). For this reason, comparisons between end of season rates for prior seasons and cumulative hospitalization rates beyond week 17 of the 2021-2022 season should be interpreted with caution and comparisons with similar late-season weekly rates is not possible since similar data from prior seasons is not available. A graph showing weekly rates for the 2021-2022 season beyond week 17 has been added to FluView.

        A total of 4,546 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2021, and May 21, 2022. The overall cumulative hospitalization rate was 15.5 per 100,000 population and the overall weekly hospitalization rate was 0.6 per 100,000 population. The weekly rate for the 2021-22 season during MMWR week 17 (1.2) was the highest weekly rate observed during the 2021-2022 season and the highest rate observed during that week since the 2010-2011 season. While the cumulative hospitalization rate for the 2021-22 season is lower than the end of-season rates observed during the 4 seasons preceding the COVID-19 pandemic (ranged from 62.0 to 102.9 per 100,000 during the 2016-17 through 2019-20 seasons), recent rates may be underestimated due to reporting delays.

        When examining rates by age, the highest rate of hospitalization per 100,000 population was among adults aged 65 and older (44.8). Among adults aged 65 and older, rates were highest among adults aged 85 and older (88.9). Among persons aged less than 65 years, hospitalization rates per 100,000 population were highest among children aged 0-4 years (19.1) followed by adults aged 50-64 years (14.4). When examining rates by race and ethnicity, the highest rate of hospitalization per 100,000 population was among non-Hispanic American Indian or Alaska Native persons (24.6), followed by non-Hispanic Black persons (18.5).

        Among 4,546 hospitalizations, 4,397 (96.7%) were associated with influenza A virus, 130 (2.9%) with influenza B virus, 5 (0.1%) with influenza A virus and influenza B virus co-infection, and 14 (0.3%) with influenza virus for which the type was not determined. Among 1035 hospitalizations with influenza A subtype information, 1026 (99.1%) were A(H3N2), and 9 (0.9%) were A(H1N1)pdm09. Based on preliminary data, of the 4,546 laboratory-confirmed influenza-associated hospitalizations, 2.3% also tested positive for SARS-CoV-2.

        Among 1,942 hospitalized adults with information on underlying medical conditions, 93.8% had at least one reported underlying medical condition, the most commonly reported were hypertension, cardiovascular disease, metabolic disorder, and obesity. Among 312 hospitalized children with information on underlying medical conditions, 66.3% had at least one reported underlying medical condition; the most commonly reported condition was asthma.

        FluSurv-Net data are used to generate national estimates of the total numbers of influenza cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available at https://www.cdc.gov/flu/about/burden...-estimates.htm



        View Full Screen

        Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
        Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
        HHS Protect Hospitalization Surveillance


        Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 20, 3,039 patients with laboratory-confirmed influenza were admitted to the hospital.

        Effective February 2, 2022, hospitals are required to report laboratory-confirmed influenza hospitalizations to HHS Protect daily. Prior to this update, reporting influenza hospitalizations was optional. See COVID-19 Guidance for Hospital Reporting and FAQspdf iconexternal icon for additional details on this guidance.



        View Chart Dataexcel icon | View Full Screen

        Additional HHS Protect hospitalization surveillance information:
        Surveillance Methods | Additional Dataexternal icon
        Mortality Surveillance

        National Center for Health Statistics (NCHS) Mortality Surveillance


        Based on NCHS mortality surveillance data available on May 26, 2022, 8.0% of the deaths that occurred during the week ending May 21, 2022 (week 20), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 6.4% for this week. Among the 1,533 PIC deaths reported for this week, 635 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and 34 listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



        View Chart Dataexcel icon | View Full Screen

        Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
        Surveillance Methods | FluView Interactive
        Influenza-Associated Pediatric Mortality


        One influenza-associated pediatric death occurring during the 2021-2022 season was reported to CDC during week 20. The death was associated with an influenza A virus for which no subtyping was performed and occurred during week 20.

        A total of 25 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


        View Full Screen

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


        Additional National and International Influenza Surveillance Information


        FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

        National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

        U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
        Additional influenza surveillance information from participating WHO member nations is available through
        FluNetexternal icon and the Global Epidemiology Reports.external icon

        WHO Collaborating Centers for Influenza:
        Australiaexternal icon, Chinaexternal icon, Japanexternal icon, the United Kingdomexternal icon, and the United States (CDC in Atlanta, Georgia)

        Europe:
        The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Controlexternal icon.

        Public Health Agency of Canada:
        The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch reportexternal icon.

        Public Health England:
        The most up-to-date influenza information from the United Kingdom is available from Public Health Englandexternal icon.

        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.

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

        https://www.cdc.gov/flu/weekly/index.htm

        Comment


        • #49

          Weekly U.S. Influenza Surveillance Report


          Updated June 3, 2022

          Note: CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review.

          Key Updates for Week 21, ending May 28, 2022

          Seasonal influenza viruses continue to circulate, and activity is increasing in parts of the country.
          Viruses


          Clinical Lab5.7%


          positive for influenza
          this week


          Public Health Lab
          The majority of viruses
          detected are influenza A(H3N2).


          Virus Characterization
          Genetic and antigenic characterization and antiviral susceptibility are summarized in this report.
          Illness

          Outpatient Respiratory Illness2.3%


          of visits to a health care provider are for respiratory illness this week
          (below baseline)


          Outpatient Respiratory Illness: Activity Map
          This week, 1 jurisdiction experienced moderate activity and 4 jurisdictions experienced high or very high activity.

          Long-term Care Facilities0.5%


          of facilities reported
          ≥ 1 influenza-positive test
          among residents this week.

          Severe Disease


          FluSurv-NET16.0 per 100,000


          cumulative hospitalization rate

          HHS Protect Hospitalizations2,660


          patients admitted to hospitals with influenza
          this week.


          NCHS Mortality7.8%


          of deaths attributed to pneumonia, influenza, or COVID-19 this week (above threshold)

          Pediatric Deaths0


          influenza-associated deaths reported this week for a total of 25 so far this season

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

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

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

          Key Points
          • Seasonal influenza viruses continue to circulate, and activity is increasing in parts of the country.
          • The majority of influenza viruses detected are A(H3N2). H3N2 viruses identified so far this season are genetically closely related to the vaccine virus. Antigenic data show that the majority of the H3N2 viruses characterized are antigenically different from the vaccine reference viruses. While the number of B/Victoria viruses circulating this season is small, the majority of the B/Victoria viruses characterized are antigenically similar to the vaccine reference virus.
          • The percentage of outpatient visits due to respiratory illness decreased slightly over the past two weeks. Influenza is contributing to levels of respiratory illness, but other respiratory viruses are also circulating. The relative contribution of influenza varies by location.
          • The numbers of hospital admissions with laboratory confirmed influenza that were reported to HHS Protect has decreased compared to last week.
          • Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). As of MMWR week 21, the overall cumulative hospitalization rate was 16.0 per 100,000 population, and the overall weekly hospitalization rate was 0.4 per 100,000 population. Reporting of recent hospital admissions can be subject to reporting delays; therefore, as hospitalization data are received each week, prior rates are updated accordingly.
          • CDC estimates that, so far this season, there have been at least 7.4 million flu illnesses, 76,000 hospitalizations, and 4,700 deaths from flu.
          • An annual flu vaccine is the best way to protect against flu. Vaccination can prevent serious outcomes in people who get vaccinated but still get sick. CDC continues to recommend that everyone ages 6 months and older get a flu vaccine as long as flu activity continues.
          • There are also prescription flu antiviral drugs that can be used to treat flu illness.
          U.S. Virologic Surveillance


          Nationally, the percentage of specimens testing positive for influenza in clinical laboratories decreased. However, activity varied by region; percent positivity increased by more than 0.1 percentage point this week in regions 4, 8, and 10, and was similar to or lower than the previous week in all other regions. Influenza A(H3N2) viruses have been the most frequently detected influenza viruses this season. Of the 12,407 influenza positives reported this season by the public health labs and also tested for SARS-CoV-2, 547 (4.4%) were also positive for SARS-CoV-2. For regional and state level data and age group distribution, please visit FluView Interactive. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
          Clinical Laboratories


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

          No. of specimens tested 57,383 2,601,090
          No. of positive specimens (%) 3,246 (5.7%) 115,582 (4.4%)
          Positive specimens by type
          Influenza A 3,228 (99.4%) 113,910 (98.6%)
          Influenza B 18 (0.6%) 1,672 (1.4%)

          View Chart Data | View Full Screen Public Health Laboratories


          The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
          No. of specimens tested 13,172 841,447
          No. of positive specimens 240 22,707
          Positive specimens by type/subtype
          Influenza A 240 (100%) 22,586 (99.5%)
          (H1N1)pdm09 0 22 (0.1%)
          H3N2 129 (100%) 17,428 (99.9%)
          H3N2v 0 1 (<0.1%)
          Subtyping not performed 111 5,135
          Influenza B 0 (0%) 121 (0.5%)
          Yamagata lineage 0 1 (2.6%)
          Victoria lineage 0 38 (97.4%)
          Lineage not performed 0 82



          View Chart Data | View Full Screen

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


          CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local public health laboratories using the Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of circulating influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir.

          CDC has genetically characterized 1,445 influenza viruses collected since October 3, 2021. H3N2 viruses identified so far this season are genetically closely related to the vaccine virus, but there are some antigenic differences that have developed as H3N2 viruses have continued to evolve.
          A/H1 5
          6B.1A 5 (100%) 5a.1 3 (60%)
          5a.2 2 (40%)
          A/H3 1,416
          3C.2a1b 1,416 (100%) 1a 3 (0.2%)
          1b 1 (0.1%)
          2a 0
          2a.1 0
          2a.2 1,412 (99.7%)
          3C.3a 0 3a 0
          B/Victoria 24
          V1A 24 (100%) V1A 0
          V1A.1 0
          V1A.3 9 (37.5%)
          V1A.3a 0
          V1A.3a.1 0
          V1A.3a.2 15 (62.5%)
          B/Yamagata 0
          Y3 0
          CDC antigenically characterizes influenza viruses by hemagglutination inhibition (HI) (H1N1pdm09, B/Victoria and B/Yamagata viruses) or neutralization-based HINT (H3N2 viruses) using antisera that ferrets make after being infected with reference viruses representing the 2021-2022 Northern Hemisphere recommended egg-based and cell or recombinant-based vaccine viruses. Antigenic differences between viruses are determined by comparing how well the antibodies made against the vaccine reference viruses recognize the circulating viruses that have been grown in cell culture. Ferret antisera are useful because antibodies raised against a particular virus can often recognize small changes in the surface proteins of other viruses. In HI assays, viruses with similar antigenic properties have antibody titer differences of less than or equal to 4-fold when compared to the reference (vaccine) virus. In HINT, viruses with similar antigenic properties have antibody neutralization titer differences of less than 8-fold. Viruses selected for antigenic characterization are a subset representing the genetic changes in the surface proteins seen in genetically characterized viruses.

          Influenza A Viruses
          • A (H1N1)pdm09: Three A(H1N1)pdm09 viruses were antigenically characterized by HI, and 2 (67%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown A/Wisconsin/588/2019-like reference viruses representing the A(H1N1)pdm09 component for the cell- and recombinant-based influenza vaccines, and 2 (67%) were well recognized by ferret antisera to egg-grown A/Victoria/2570/2019-like reference viruses representing the A(H1N1)pdm09 component for the egg-based influenza vaccines.
          • A (H3N2): A subset of 115 A(H3N2) viruses were antigenically characterized by HINT, and 4 (3%) were well recognized (reacting at titers that were within 8-fold of the homologous virus titer) by ferret antisera to cell-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for the cell- and recombinant-based influenza vaccines, and 20 (17%) were well recognized by ferret antisera to egg-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for egg-based influenza vaccines.

          Influenza B Viruses
          • B/Victoria: Fifteen B/Victoria lineage viruses were antigenically characterized by HI, and 11 (73%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for the cell- and recombinant-based influenza vaccines, and 11 (73%) were well recognized by ferret antisera to egg-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for egg-based influenza vaccines.
          • B/Yamagata: No influenza B/Yamagata-lineage viruses were available for antigenic characterization.

          Assessment of Virus Susceptibility to Antiviral Medications

          CDC assesses susceptibility of influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Information about antiviral susceptibility test methods can be found at U.S. Influenza Surveillance: Purpose and Methods | CDC.

          Viruses collected in the United States since October 3, 2021, were tested for antiviral susceptibility as follows:
          Neuraminidase
          Inhibitors
          Oseltamivir Viruses
          Tested
          1,466 5 1,437 24 0
          Reduced
          Inhibition
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          Highly
          Reduced
          Inhibition
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          Peramivir Viruses
          Tested
          1,466 5 1,437 24 0
          Reduced
          Inhibition
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          Highly
          Reduced
          Inhibition
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          Zanamivir Viruses
          Tested
          1,466 5 1,437 24 0
          Reduced
          Inhibition
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          Highly
          Reduced
          Inhibition
          (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
          PA Cap-Dependent Endonuclease Inhibitor Baloxavir Viruses
          Tested
          1,453 5 1,424 24 0
          Reduced
          Susceptibility
          1 (0.1%) (0.0%) 1 (0.1%) (0.0%) (0.0%)

          One A(H3N2) virus had a PA-I38M amino acid substitution previously associated with reduced baloxavir susceptibility and showed ~8-fold reduced susceptibility to baloxavir in vitro.

          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, use of these antivirals for treatment and prevention of influenza A virus infection is not recommended, and data from adamantane resistance testing are not presented.
          Outpatient Respiratory Illness Surveillance


          The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
          Outpatient Respiratory Illness Visits


          Nationwide during week 21, 2.3% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. This decreased slightly over the past two weeks. Eight of the 10 HHS regions are below their region-specific baselines; regions 4 and 10 are above their respective baselines. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



          * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


          View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


          More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

          The percentage of visits for respiratory illness reported in ILINet is trending upward in all age groups (0-4 years, 5-24 years, 25-49 years, 50-64 years, and 65+ years).



          * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

          View Chart Data | View Full Screen
          Outpatient Respiratory Illness Activity Map


          Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
          Week 21
          (Week ending
          May 28, 2022)
          Week 20
          (Week ending
          May 21, 2022)
          Week 21
          (Week ending
          May 28, 2022)
          Week 20
          (Week ending
          May 21, 2022)
          Very High 1 0 4 4
          High 3 2 20 20
          Moderate 1 7 23 26
          Low 9 9 90 94
          Minimal 40 37 504 514
          Insufficient Data 1 0 288 271



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

          Additional information about medically attended visits for ILI for current and past seasons:
          Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
          Long-term Care Facility (LTCF) Surveillance


          LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 21, 67 (0.5%) of 14,103 reporting LTCFs reported at least one influenza positive test among their residents.



          View Chart Data | View Full Screen

          Additional information about long-term care facility surveillance:
          Surveillance Methods | Additional Data
          Hospitalization Surveillance

          FluSurv-NET


          The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. As data are received each week, prior case counts and rates are updated accordingly.

          Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). For this reason, comparisons between end of season rates for prior seasons and cumulative hospitalization rates beyond week 17 of the 2021-2022 season should be interpreted with caution and comparisons with similar late-season weekly rates is not possible since similar data from prior seasons is not available.

          A total of 4,702 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2021, and May 28, 2022. The overall cumulative hospitalization rate was 16.0 per 100,000 population and the overall weekly hospitalization rate was 0.4 per 100,000 population. The weekly rate for the 2021-22 season during MMWR week 17 (1.2) was the highest weekly rate observed during the 2021-22 season and the highest rate observed during any week 17 since the 2010-2011 season. While the cumulative hospitalization rate for the 2021-22 season is lower than the end of-season rates observed during the 4 seasons preceding the COVID-19 pandemic (ranged from 62.0 to 102.9 per 100,000 during the 2016-17 through 2019-20 seasons), recent rates may be underestimated due to reporting delays.

          When examining rates by age, the highest rate of hospitalization per 100,000 population was among adults aged 65 and older (46.4). Among adults aged 65 and older, rates were highest among adults aged 85 and older (92.2). Among persons aged less than 65 years, hospitalization rates per 100,000 population were highest among children aged 0-4 years (20.1) followed by adults aged 50-64 years (14.9). When examining rates by race and ethnicity, the highest rate of hospitalization per 100,000 population was among non-Hispanic American Indian or Alaska Native persons (25.5), followed by non-Hispanic Black persons (19.1).

          Among 4,702 hospitalizations, 4,552 (96.8%) were associated with influenza A virus, 131 (2.8%) with influenza B virus, 5 (0.1%) with influenza A virus and influenza B virus co-infection, and 14 (0.3%) with influenza virus for which the type was not determined. Among 1,076 hospitalizations with influenza A subtype information, 1,066 (99.1%) were A(H3N2), and 10 (0.9%) were A(H1N1)pdm09. Based on preliminary data, of the 4,702 laboratory-confirmed influenza-associated hospitalizations, 2.2% also tested positive for SARS-CoV-2.

          Among 2,071 hospitalized adults with information on underlying medical conditions, 93.7% had at least one reported underlying medical condition, the most commonly reported were hypertension, cardiovascular disease, metabolic disorder, and obesity. Among 329 hospitalized children with information on underlying medical conditions, 65.3% had at least one reported underlying medical condition; the most commonly reported was asthma.

          FluSurv-Net data are used to generate national estimates of the total numbers of influenza cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available at https://www.cdc.gov/flu/about/burden...-estimates.htm



          View Full Screen

          Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
          Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
          HHS Protect Hospitalization Surveillance


          Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 21, 2,660 patients with laboratory-confirmed influenza were admitted to the hospital.

          Effective February 2, 2022, hospitals are required to report laboratory-confirmed influenza hospitalizations to HHS Protect daily. Prior to this update, reporting influenza hospitalizations was optional. See COVID-19 Guidance for Hospital Reporting and FAQs for additional details on this guidance.



          View Chart Data | View Full Screen

          Additional HHS Protect hospitalization surveillance information:
          Surveillance Methods | Additional Data
          Mortality Surveillance

          National Center for Health Statistics (NCHS) Mortality Surveillance


          Based on NCHS mortality surveillance data available on June 2, 2022, 7.8% of the deaths that occurred during the week ending May 28, 2022 (week 21), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 6.3% for this week. Among the 986 PIC deaths reported for this week, 483 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and 15 listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.

          Starting June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system will be undergoing a system-wide upgrade. Because of this upgrade period, certain NVSS surveillance datasets and reports will be paused temporarily, including those used to evaluate pneumonia, influenza, and COVID-19 deaths. NCHS mortality data will not be published in FluView or FluView Interactive for MMWR weeks 22 and 23. Data updates are expected to resume for week 24.



          View Chart Data | View Full Screen

          Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
          Surveillance Methods | FluView Interactive
          Influenza-Associated Pediatric Mortality


          No influenza-associated pediatric deaths were reported to CDC during week 21.

          A total of 25 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


          View Full Screen

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


          Additional National and International Influenza Surveillance Information


          FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

          National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

          U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
          Additional influenza surveillance information from participating WHO member nations is available through
          FluNet and the Global Epidemiology Reports.

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

          Europe:
          The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

          Public Health Agency of Canada:
          The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

          Public Health England:
          The most up-to-date influenza information from the United Kingdom is available from Public Health England.

          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.

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

          https://www.cdc.gov/flu/weekly/index.htm

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            • #51
              Weekly U.S. Influenza Surveillance Report


              Updated June 10, 2022

              Note: CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review.

              Key Updates for Week 22, ending June 4, 2022

              Seasonal influenza viruses continue to circulate, and activity is increasing in parts of the country.
              Viruses


              Clinical Lab5.9%


              positive for influenza
              this week


              Public Health Lab
              The majority of viruses
              detected are influenza A(H3N2).


              Virus Characterization
              Genetic and antigenic characterization and antiviral susceptibility are summarized in this report.
              Illness

              Outpatient Respiratory Illness2.3%


              of visits to a health care provider are for respiratory illness this week
              (below baseline)


              Outpatient Respiratory Illness: Activity Map
              This week, 2 jurisdictions experienced high activity and 2 jurisdictions experienced very high activity.

              Long-term Care Facilities0.5%


              of facilities reported
              ≥ 1 influenza-positive test
              among residents this week.

              Severe Disease


              FluSurv-NET16.7 per 100,000


              cumulative hospitalization rate

              HHS Protect Hospitalizations2,608


              patients admitted to hospitals with influenza
              this week.


              NCHS Mortality
              No report this week due to system-wide coding upgrade.

              Pediatric Deaths3


              influenza-associated deaths reported this week with a total of 28 so far this season

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

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

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

              Key Points
              • Seasonal influenza viruses continue to circulate, and activity is increasing in parts of the country.
              • The majority of influenza viruses detected are A(H3N2). H3N2 viruses identified so far this season are genetically closely related to the vaccine virus. Antigenic data show that the majority of the H3N2 viruses characterized are antigenically different from the vaccine reference viruses. While the number of B/Victoria viruses circulating this season is small, the majority of the B/Victoria viruses characterized are antigenically similar to the vaccine reference virus.
              • The percentage of outpatient visits due to respiratory illness decreased slightly over the past three weeks. Influenza is contributing to levels of respiratory illness, but other respiratory viruses are also circulating. The relative contribution of influenza varies by location.
              • The number of hospital admissions with laboratory confirmed influenza that were reported to HHS Protect remained stable compared to last week, but is trending downwards.
              • Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). As of MMWR week 22, the overall cumulative hospitalization rate was 16.7 per 100,000 population, and the overall weekly hospitalization rate was 0.3 per 100,000 population. Reporting of recent hospital admissions can be subject to reporting delays; therefore, as hospitalization data are received each week, prior rates are updated accordingly.
              • Three influenza-associated pediatric deaths were reported this week. A total of 28 influenza-associated pediatric deaths occurring this season have been reported.
              • CDC estimates that, so far this season, there have been at least 7.8 million flu illnesses, 80,000 hospitalizations, and 4,900 deaths from flu.
              • An annual flu vaccine is the best way to protect against flu. Vaccination can prevent serious outcomes in people who get vaccinated but still get sick. CDC continues to recommend that everyone ages 6 months and older get a flu vaccine as long as flu activity continues.
              • There are also prescription flu antiviral drugs that can be used to treat flu illness.
              U.S. Virologic Surveillance


              Nationally, the percentage of specimens testing positive for influenza in clinical laboratories was similar to the previous week. However, activity varied by region; percent positivity increased by more than 0.1 percentage point this week in Region 9 and was similar to or lower than the previous week in all other regions. Influenza A(H3N2) viruses have been the most frequently detected influenza viruses this season. Of the 12,805 influenza positives reported this season by the public health labs and also tested for SARS-CoV-2, 555 (4.3%) were also positive for SARS-CoV-2. For regional and state level data and age group distribution, please visit FluView Interactive. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
              Clinical Laboratories


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

              No. of specimens tested 57,221 2,674,680
              No. of positive specimens (%) 3,365 (5.9%) 120,152 (4.5%)
              Positive specimens by type
              Influenza A 3,332 (99.0%) 118,420 (98.6%)
              Influenza B 33 (1.0%) 1,732 (1.4%)

              View Chart Data | View Full Screen Public Health Laboratories


              The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
              No. of specimens tested 12,378 854,963
              No. of positive specimens 182 23,277
              Positive specimens by type/subtype
              Influenza A 182 (100%) 23,154 (99.5%)
              (H1N1)pdm09 1 (0.9%) 25 (0.1%)
              H3N2 110 (99.1%) 18,055 (99.9%)
              H3N2v 0 1 (<0.1%)
              Subtyping not performed 71 5,073
              Influenza B 0 (0%) 123 (0.5%)
              Yamagata lineage 0 1 (2.4%)
              Victoria lineage 0 40 (97.6%)
              Lineage not performed 0 82



              View Chart Data | View Full Screen

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


              CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local public health laboratories using the Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of circulating influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir.

              CDC has genetically characterized 1,505 influenza viruses collected since October 3, 2021. H3N2 viruses identified so far this season are genetically closely related to the vaccine virus, but there are some antigenic differences that have developed as H3N2 viruses have continued to evolve.
              A/H1 6
              6B.1A 6 (100%) 5a.1 4 (66.7%)
              5a.2 2 (33.3%)
              A/H3 1,474
              3C.2a1b 1,474 (100%) 1a 3 (0.2%)
              1b 1 (0.1%)
              2a 0
              2a.1 0
              2a.2 1,470 (99.7%)
              3C.3a 0 3a 0
              B/Victoria 24
              V1A 24 (100%) V1A 0
              V1A.1 0
              V1A.3 9 (37.5%)
              V1A.3a 0
              V1A.3a.1 0
              V1A.3a.2 15 (62.5%)
              B/Yamagata 0
              Y3 0
              CDC antigenically characterizes influenza viruses by hemagglutination inhibition (HI) (H1N1pdm09, B/Victoria and B/Yamagata viruses) or neutralization-based HINT (H3N2 viruses) using antisera that ferrets make after being infected with reference viruses representing the 2021-2022 Northern Hemisphere recommended egg-based and cell or recombinant-based vaccine viruses. Antigenic differences between viruses are determined by comparing how well the antibodies made against the vaccine reference viruses recognize the circulating viruses that have been grown in cell culture. Ferret antisera are useful because antibodies raised against a particular virus can often recognize small changes in the surface proteins of other viruses. In HI assays, viruses with similar antigenic properties have antibody titer differences of less than or equal to 4-fold when compared to the reference (vaccine) virus. In HINT, viruses with similar antigenic properties have antibody neutralization titer differences of less than 8-fold. Viruses selected for antigenic characterization are a subset representing the genetic changes in the surface proteins seen in genetically characterized viruses.

              Influenza A Viruses
              • A (H1N1)pdm09: Three A(H1N1)pdm09 viruses were antigenically characterized by HI, and 2 (67%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown A/Wisconsin/588/2019-like reference viruses representing the A(H1N1)pdm09 component for the cell- and recombinant-based influenza vaccines, and 2 (67%) were well recognized by ferret antisera to egg-grown A/Victoria/2570/2019-like reference viruses representing the A(H1N1)pdm09 component for the egg-based influenza vaccines.
              • A (H3N2): A subset of 115 A(H3N2) viruses were antigenically characterized by HINT, and 4 (3%) were well recognized (reacting at titers that were within 8-fold of the homologous virus titer) by ferret antisera to cell-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for the cell- and recombinant-based influenza vaccines, and 20 (17%) were well recognized by ferret antisera to egg-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for egg-based influenza vaccines.

              Influenza B Viruses
              • B/Victoria: Fifteen B/Victoria lineage viruses were antigenically characterized by HI, and 11 (73%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for the cell- and recombinant-based influenza vaccines, and 11 (73%) were well recognized by ferret antisera to egg-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for egg-based influenza vaccines.
              • B/Yamagata: No influenza B/Yamagata-lineage viruses were available for antigenic characterization.

              Assessment of Virus Susceptibility to Antiviral Medications

              CDC assesses susceptibility of influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Information about antiviral susceptibility test methods can be found at U.S. Influenza Surveillance: Purpose and Methods | CDC.

              Viruses collected in the United States since October 3, 2021, were tested for antiviral susceptibility as follows:
              Neuraminidase
              Inhibitors
              Oseltamivir Viruses
              Tested
              1,542 6 1,512 24 0
              Reduced
              Inhibition
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              Highly
              Reduced
              Inhibition
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              Peramivir Viruses
              Tested
              1,512 6 1,512 24 0
              Reduced
              Inhibition
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              Highly
              Reduced
              Inhibition
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              Zanamivir Viruses
              Tested
              1,542 6 1,512 24 0
              Reduced
              Inhibition
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              Highly
              Reduced
              Inhibition
              (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
              PA Cap-Dependent Endonuclease Inhibitor Baloxavir Viruses
              Tested
              1,538 6 1,508 24 0
              Reduced
              Susceptibility
              1 (0.1%) (0.0%) 1 (0.1%) (0.0%) (0.0%)

              One A(H3N2) virus had a PA-I38M amino acid substitution previously associated with reduced baloxavir susceptibility and showed ~8-fold reduced susceptibility to baloxavir in vitro.

              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, use of these antivirals for treatment and prevention of influenza A virus infection is not recommended, and data from adamantane resistance testing are not presented.
              Outpatient Respiratory Illness Surveillance


              The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
              Outpatient Respiratory Illness Visits


              Nationwide during week 22, 2.3% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. This decreased slightly over the past three weeks. Eight of the 10 HHS regions are at or below their region-specific baselines; regions 4 and 10 are above their respective baselines. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



              * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


              View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


              More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

              The percentage of visits for respiratory illness reported in ILINet has been trending upward for all age groups but decreased this week in the 5-24 year age group compared with the previous week.



              * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

              View Chart Data | View Full Screen
              Outpatient Respiratory Illness Activity Map


              Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
              Week 22
              (Week ending
              June 4, 2022)
              Week 21
              (Week ending
              May 28, 2022)
              Week 22
              (Week ending
              June 4, 2022)
              Week 21
              (Week ending
              May 28, 2022)
              Very High 2 1 5 5
              High 2 2 20 21
              Moderate 0 2 21 22
              Low 8 7 79 89
              Minimal 42 42 514 517
              Insufficient Data 1 1 290 275



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

              Additional information about medically attended visits for ILI for current and past seasons:
              Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
              Long-term Care Facility (LTCF) Surveillance


              LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 22, 76 (0.5%) of 14,481 reporting LTCFs reported at least one influenza positive test among their residents.



              View Chart Data | View Full Screen

              Additional information about long-term care facility surveillance:
              Surveillance Methods | Additional Data
              Hospitalization Surveillance

              FluSurv-NET


              The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. As data are received each week, prior case counts and rates are updated accordingly.

              Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance has been extended beyond the typical end date of April 30 (MMWR Week 17). For this reason, comparisons between end of season rates for prior seasons and cumulative hospitalization rates beyond week 17 of the 2021-2022 season should be interpreted with caution and comparisons with similar late-season weekly rates is not possible since similar data from prior seasons is not available.

              A total of 4,898 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2021, and June 4, 2022. The overall cumulative hospitalization rate was 16.7 per 100,000 population and the overall weekly hospitalization rate was 0.3 per 100,000 population. The weekly rate for the 2021-22 season during MMWR week 17 (1.2) was the highest weekly rate observed during the 2021-22 season and the highest rate observed during any week 17 since the 2010-2011 season. While the cumulative hospitalization rate for the 2021-22 season is lower than the end of-season rates observed during the 4 seasons preceding the COVID-19 pandemic (ranged from 62.0 to 102.9 per 100,000 during the 2016-17 through 2019-20 seasons), recent rates may be underestimated due to reporting delays.

              When examining rates by age, the highest rate of hospitalization per 100,000 population was among adults aged 65 and older (48.4). Among adults aged 65 and older, rates were highest among adults aged 85 and older (95.7). Among persons aged <65 years, hospitalization rates per 100,000 population were highest among children aged 0-4 years (21.2) followed by adults aged 50-64 years (15.4). When examining rates by race and ethnicity, the highest rate of hospitalization per 100,000 population was among non-Hispanic American Indian or Alaska Native persons (29), followed by non-Hispanic Black persons (19.9).

              Among 4,898 hospitalizations, 4,742 (96.8%) were associated with influenza A virus, 138 (2.8%) with influenza B virus, 5 (0.1%) with influenza A virus and influenza B virus co-infection, and 13 (0.3%) with influenza virus for which the type was not determined. Among 1127 hospitalizations with influenza A subtype information, 1114 (98.8%) were A(H3N2), and 13 (1.2%) were A(H1N1)pdm09. Based on preliminary data, of the 4,898 laboratory-confirmed influenza-associated hospitalizations, 2.3% also tested positive for SARS-CoV-2.

              Among 2,177 hospitalized adults with information on underlying medical conditions, 93.7% had at least one reported underlying medical condition, the most commonly reported were hypertension, cardiovascular disease, metabolic disorder, and obesity. Among 337 hospitalized children with information on underlying medical conditions, 65.3% had at least one reported underlying medical condition; the most commonly reported was asthma.

              FluSurv-Net data are used to generate national estimates of the total numbers of influenza cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available at https://www.cdc.gov/flu/about/burden...-estimates.htm



              View Full Screen

              Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
              Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
              HHS Protect Hospitalization Surveillance


              Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 22, 2,608 patients with laboratory-confirmed influenza were admitted to the hospital.

              Effective February 2, 2022, hospitals are required to report laboratory-confirmed influenza hospitalizations to HHS Protect daily. Prior to this update, reporting influenza hospitalizations was optional. See COVID-19 Guidance for Hospital Reporting and FAQs for additional details on this guidance.



              View Chart Data | View Full Screen

              Additional HHS Protect hospitalization surveillance information:
              Surveillance Methods | Additional Data
              Mortality Surveillance

              National Center for Health Statistics (NCHS) Mortality Surveillance


              Starting June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system is undergoing a system-wide upgrade. Because of this upgrade period, certain NVSS surveillance datasets and reports will be paused temporarily, including those used to evaluate pneumonia, influenza, and COVID-19 deaths. NCHS mortality data will not be published in FluView or FluView Interactive for MMWR weeks 22 and 23. Data updates are expected to resume for week 24.



              Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
              Surveillance Methods | FluView Interactive
              Influenza-Associated Pediatric Mortality


              Three influenza-associated pediatric deaths were reported to CDC during week 22. Two deaths were associated with influenza A viruses for which no subtyping was performed and occurred during weeks 19 and 21 (the weeks ending May 14, 2022, and May 28, 2022). One death was associated with an influenza A (H3) virus and occurred during week 20 (the week ending May 28, 2022).

              A total of 28 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


              View Full Screen

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


              Additional National and International Influenza Surveillance Information


              FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

              National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

              U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
              Additional influenza surveillance information from participating WHO member nations is available through
              FluNet and the Global Epidemiology Reports.

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

              Europe:
              The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

              Public Health Agency of Canada:
              The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

              Public Health England:
              The most up-to-date influenza information from the United Kingdom is available from Public Health England.

              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.

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

              https://www.cdc.gov/flu/weekly/index.htm

              Comment


              • #52

                Weekly U.S. Influenza Surveillance Report


                Updated June 17, 2022

                The Week 23 (ending June 11, 2022) FluView report is the last full FluView report of the 2021-2022 season. An abbreviated report will be published during the summer, and the first full report of the 2022-23 season will be published on October 14, 2022.


                Note: CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review.

                Key Updates for Week 23, ending June 11, 2022

                Seasonal influenza activity is decreasing nationally.
                Viruses


                Clinical Lab3.4%


                positive for influenza
                this week


                Public Health Lab
                The majority of viruses
                detected are influenza A(H3N2).


                Virus Characterization
                Genetic and antigenic characterization and antiviral susceptibility are summarized in this report.
                Illness

                Outpatient Respiratory Illness2.1%


                of visits to a health care provider are for respiratory illness this week
                (below baseline)


                Outpatient Respiratory Illness: Activity Map
                This week, 3 jurisdictions experienced high activity and 0 jurisdictions experienced very high activity.

                Long-term Care Facilities0.4%


                of facilities reported
                ≥ 1 influenza-positive test
                among residents this week.

                Severe Disease


                FluSurv-NET17.1 per 100,000


                cumulative hospitalization rate

                HHS Protect Hospitalizations2,089


                patients admitted to hospitals with influenza
                this week.


                NCHS Mortality
                No report this week due to system-wide coding upgrade.

                Pediatric Deaths1


                influenza-associated death reported this week with a total of 29 so far this season

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

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

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

                Key Points
                • Seasonal influenza activity is decreasing nationally.
                • This week is the last full version of FluView for the 2021-2022 influenza season. Starting with week 24, an abbreviated summer version of FluView will be published. The full version is expected to resume for week 40 of 2022, which is the start of the 2022-2023 influenza season.
                • The majority of influenza viruses detected are A(H3N2). H3N2 viruses identified so far this season are genetically closely related to the vaccine virus. Antigenic data show that the majority of the H3N2 viruses characterized are antigenically different from the vaccine reference viruses. While the number of B/Victoria viruses circulating this season is small, the majority of the B/Victoria viruses characterized are antigenically similar to the vaccine reference virus.
                • The percentage of outpatient visits due to respiratory illness has decreased compared to last week and has trended downward over the past four weeks. Influenza is contributing to levels of respiratory illness, but other respiratory viruses are also circulating. The relative contribution of influenza varies by location.
                • The number of hospital admissions with laboratory confirmed influenza that were reported to HHS Protect decreased compared to last week and has been trending downward since late April.
                • Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance was extended beyond the typical end date of April 30 (MMWR Week 17) to June 11 (MMWR Week 23). As of MMWR Week 23, the overall cumulative hospitalization rate was 17.1 per 100,000 population, and the overall weekly hospitalization rate was 0.3 per 100,000 population.
                • One influenza-associated pediatric death was reported this week. A total of 29 influenza-associated pediatric deaths occurring this season have been reported.
                • CDC estimates that, so far this season, there have been at least 8 million flu illnesses, 82,000 hospitalizations, and 5,000 deaths from flu.
                • An annual flu vaccine is the best way to protect against flu. Vaccination can prevent serious outcomes in people who get vaccinated but still get sick. CDC continues to recommend that everyone ages 6 months and older get a flu vaccine as long as flu activity continues.
                • There are also prescription flu antiviral drugs that can be used to treat flu illness.
                U.S. Virologic Surveillance


                The percentage of specimens testing positive for influenza in clinical laboratories was lower than the previous week nationally and in all regions. Influenza A(H3N2) viruses have been the most frequently detected influenza viruses this season. Of the 13,275 influenza positives reported this season by the public health labs and also tested for SARS-CoV-2, 563 (4.2%) were also positive for SARS-CoV-2. For regional and state level data and age group distribution, please visit FluView Interactive. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
                Clinical Laboratories


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

                No. of specimens tested 55,572 2,746,400
                No. of positive specimens (%) 1,877 (3.4%) 122,502 (4.5%)
                Positive specimens by type
                Influenza A 1,854 (98.8%) 120,734 (98.6%)
                Influenza B 23 (1.2%) 1,768 (1.4%)

                View Chart Data | View Full Screen Public Health Laboratories


                The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage.
                No. of specimens tested 14,270 873,589
                No. of positive specimens 280 24,098
                Positive specimens by type/subtype
                Influenza A 278 (99.3%) 23,972 (99.5%)
                (H1N1)pdm09 0 25 (0.1%)
                H3N2 176 (100%) 18,663 (99.9%)
                H3N2v 0 1 (<0.1%)
                Subtyping not performed 102 5,283
                Influenza B 2 (0.7%) 126 (0.5%)
                Yamagata lineage 0 1 (2.4%)
                Victoria lineage 0 40 (97.6%)
                Lineage not performed 2 85



                View Chart Data | View Full Screen

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


                CDC performs genetic and antigenic characterization of U.S. viruses submitted from state and local public health laboratories using the Right Size Roadmap submission guidance. These data are used to compare how similar the currently circulating influenza viruses are to the reference viruses representing viruses contained in the current influenza vaccines. The data are also used to monitor evolutionary changes that continually occur in influenza viruses circulating in humans. CDC also tests susceptibility of circulating influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir.

                CDC has genetically characterized 1,600 influenza viruses collected since October 3, 2021. H3N2 viruses identified so far this season are genetically closely related to the vaccine virus, but there are some antigenic differences that have developed as H3N2 viruses have continued to evolve.
                A/H1 9
                6B.1A 9 (100%) 5a.1 7 (77.8%)
                5a.2 2 (22.2%)
                A/H3 1,567
                3C.2a1b 1,567 (100%) 1a 3 (0.2%)
                1b 1 (0.1%)
                2a 0
                2a.1 0
                2a.2 1,563 (99.7%)
                3C.3a 0 3a 0
                B/Victoria 24
                V1A 24 (100%) V1A 0
                V1A.1 0
                V1A.3 9 (37.5%)
                V1A.3a 0
                V1A.3a.1 0
                V1A.3a.2 15 (62.5%)
                B/Yamagata 0
                Y3 0
                CDC antigenically characterizes influenza viruses by hemagglutination inhibition (HI) (H1N1pdm09, B/Victoria and B/Yamagata viruses) or neutralization-based HINT (H3N2 viruses) using antisera that ferrets make after being infected with reference viruses representing the 2021-2022 Northern Hemisphere recommended egg-based and cell or recombinant-based vaccine viruses. Antigenic differences between viruses are determined by comparing how well the antibodies made against the vaccine reference viruses recognize the circulating viruses that have been grown in cell culture. Ferret antisera are useful because antibodies raised against a particular virus can often recognize small changes in the surface proteins of other viruses. In HI assays, viruses with similar antigenic properties have antibody titer differences of less than or equal to 4-fold when compared to the reference (vaccine) virus. In HINT, viruses with similar antigenic properties have antibody neutralization titer differences of less than 8-fold. Viruses selected for antigenic characterization are a subset representing the genetic changes in the surface proteins seen in genetically characterized viruses.

                Influenza A Viruses
                • A (H1N1)pdm09: Three A(H1N1)pdm09 viruses were antigenically characterized by HI, and 2 (67%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown A/Wisconsin/588/2019-like reference viruses representing the A(H1N1)pdm09 component for the cell- and recombinant-based influenza vaccines, and 2 (67%) were well recognized by ferret antisera to egg-grown A/Victoria/2570/2019-like reference viruses representing the A(H1N1)pdm09 component for the egg-based influenza vaccines.
                • A (H3N2): A subset of 117 A(H3N2) viruses were antigenically characterized by HINT, and 4 (3%) were well recognized (reacting at titers that were within 8-fold of the homologous virus titer) by ferret antisera to cell-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for the cell- and recombinant-based influenza vaccines, and 21 (18%) were well recognized by ferret antisera to egg-grown A/Cambodia/E0826360/2020-like reference viruses representing the A(H3N2) component for egg-based influenza vaccines.

                Influenza B Viruses
                • B/Victoria: Fifteen B/Victoria lineage viruses were antigenically characterized by HI, and 11 (73%) were well recognized (reacting at titers that were within 4-fold of the homologous virus titer) by ferret antisera to cell-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for the cell- and recombinant-based influenza vaccines, and 11 (73%) were well recognized by ferret antisera to egg-grown B/Washington/02/2019-like reference viruses representing the B/Victoria component for egg-based influenza vaccines.
                • B/Yamagata: No influenza B/Yamagata-lineage viruses were available for antigenic characterization.

                Assessment of Virus Susceptibility to Antiviral Medications

                CDC assesses susceptibility of influenza viruses to antiviral medications including the neuraminidase inhibitors (oseltamivir, zanamivir, and peramivir) and the PA endonuclease inhibitor baloxavir using next generation sequence analysis supplemented by laboratory assays. Information about antiviral susceptibility test methods can be found at U.S. Influenza Surveillance: Purpose and Methods | CDC.

                Viruses collected in the United States since October 3, 2021, were tested for antiviral susceptibility as follows:
                Neuraminidase
                Inhibitors
                Oseltamivir Viruses
                Tested
                1,615 9 1,582 24 0
                Reduced
                Inhibition
                (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                Highly
                Reduced
                Inhibition
                1 (0.1%) 1 (11.1%) (0.0%) (0.0%) (0.0%)
                Peramivir Viruses
                Tested
                1,615 9 1,582 24 0
                Reduced
                Inhibition
                (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                Highly
                Reduced
                Inhibition
                1 (0.1%) 1 (11.1%) (0.0%) (0.0%) (0.0%)
                Zanamivir Viruses
                Tested
                1,615 9 1,582 24 0
                Reduced
                Inhibition
                (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                Highly
                Reduced
                Inhibition
                (0.0%) (0.0%) (0.0%) (0.0%) (0.0%)
                PA Cap-Dependent Endonuclease Inhibitor Baloxavir Viruses
                Tested
                1,613 9 1,580 24 0
                Reduced
                Susceptibility
                1 (0.1%) (0.0%) 1 (0.1%) (0.0%) (0.0%)

                One A(H1N1)pdm09 virus had a NA-H275Y amino acid substitution, a marker of oseltamivir resistance.

                One A(H3N2) virus had a PA-I38M amino acid substitution previously associated with reduced baloxavir susceptibility and showed ~8-fold reduced susceptibility to baloxavir in vitro.

                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, use of these antivirals for treatment and prevention of influenza A virus infection is not recommended, and data from adamantane resistance testing are not presented.
                Outpatient Respiratory Illness Surveillance


                The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                Outpatient Respiratory Illness Visits


                Nationwide during week 23, 2.1% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. This is a decrease compared to week 22 and has been trending downward over the past four weeks. Nine of the 10 HHS regions are at or below their region-specific baselines; Region 3 is above their respective baseline. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                The percentage of visits for respiratory illness reported in ILINet has been trending downward or remaining stable for all age groups.



                * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                View Chart Data | View Full Screen
                Outpatient Respiratory Illness Activity Map


                Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                Week 23
                (Week ending
                Jun. 11, 2022)
                Week 22
                (Week ending
                Jun. 4, 2022)
                Week 23
                (Week ending
                Jun. 11, 2022)
                Week 22
                (Week ending
                Jun. 4, 2022)
                Very High 0 1 2 6
                High 3 3 13 20
                Moderate 2 0 26 21
                Low 5 9 60 79
                Minimal 45 41 548 523
                Insufficient Data 0 1 280 280



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

                Additional information about medically attended visits for ILI for current and past seasons:
                Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                Long-term Care Facility (LTCF) Surveillance


                LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 23, 55 (0.4%) of 14,471 reporting LTCFs reported at least one influenza positive test among their residents.



                View Chart Data | View Full Screen

                Additional information about long-term care facility surveillance:
                Surveillance Methods | Additional Data
                Hospitalization Surveillance

                FluSurv-NET


                The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. As data are received each week, prior case counts and rates are updated accordingly.

                Due to late-season activity during the 2021-2022 season, FluSurv-NET surveillance was extended beyond the typical end date of April 30 (MMWR Week 17) to June 11 (MMWR Week 23). For this reason, comparisons between end of season rates for prior seasons and cumulative hospitalization rates beyond week 17 of the 2021-2022 season should be interpreted with caution and comparisons with similar late-season weekly rates are not possible since similar data from prior seasons is not available.

                A total of 5,019 laboratory-confirmed influenza-associated hospitalizations were reported by FluSurv-NET sites between October 1, 2021, and June 11, 2022. The overall cumulative hospitalization rate was 17.1 per 100,000 population and the overall weekly hospitalization rate was 0.3 per 100,000 population. The weekly rate for the 2021-22 season during MMWR week 17 (1.2) was the highest weekly rate observed during the 2021-22 season and the highest rate observed during any week 17 since the 2010-2011 season. While the cumulative hospitalization rate for the 2021-22 season is lower than the end of-season rates observed during the four seasons preceding the COVID-19 pandemic (ranged from 62.0 to 102.9 per 100,000 during the 2016-17 through 2019-20 seasons), recent rates may be underestimated due to reporting delays.

                When examining rates by age, the highest rate of hospitalization per 100,000 population was among adults aged 65 and older (49.6). Among adults aged 65 and older, rates were highest among adults aged 85 and older (98.6). Among persons aged less than 65 years, hospitalization rates per 100,000 population were highest among children aged 0-4 years (21.8) followed by adults aged 50-64 years (15.8). When examining rates by race and ethnicity, the highest rate of hospitalization per 100,000 population was among non-Hispanic American Indian or Alaska Native persons (31.4), followed by non-Hispanic Black persons (20.5).

                Among 5,019 hospitalizations, 4,843 (96.5%) were associated with influenza A virus, 147 (2.9%) with influenza B virus, 5 (0.1%) with influenza A virus and influenza B virus co-infection, and 24 (0.5%) with influenza virus for which the type was not determined. Among 1153 hospitalizations with influenza A subtype information, 1139 (98.8%) were A(H3N2), and 14 (1.2%) were A(H1N1)pdm09. Based on preliminary data, of the 5,019 laboratory-confirmed influenza-associated hospitalizations, 2.3% also tested positive for SARS-CoV-2.

                Among 2,320 hospitalized adults with information on underlying medical conditions, 93.4% had at least one reported underlying medical condition, the most commonly reported were hypertension, cardiovascular disease, metabolic disorder, and obesity. Among 359 hospitalized children with information on underlying medical conditions, 64.6% had at least one reported underlying medical condition; the most commonly reported was asthma.

                FluSurv-Net data are used to generate national estimates of the total numbers of influenza cases, medical visits, hospitalizations, and deaths. This season, CDC is reporting preliminary cumulative in-season estimates, which are available at https://www.cdc.gov/flu/about/burden...-estimates.htm



                View Full Screen

                Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                HHS Protect Hospitalization Surveillance


                Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 23, 2,089 patients with laboratory-confirmed influenza were admitted to the hospital.

                Effective February 2, 2022, hospitals are required to report laboratory-confirmed influenza hospitalizations to HHS Protect daily. Prior to this update, reporting influenza hospitalizations was optional. See COVID-19 Guidance for Hospital Reporting and FAQs for additional details on this guidance.



                View Chart Data | View Full Screen

                Additional HHS Protect hospitalization surveillance information:
                Surveillance Methods | Additional Data
                Mortality Surveillance

                National Center for Health Statistics (NCHS) Mortality Surveillance


                Starting June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system is undergoing a system-wide upgrade. Because of this upgrade period, certain NVSS surveillance datasets and reports will be paused temporarily, including those used to evaluate pneumonia, influenza, and COVID-19 deaths. NCHS mortality data will not be published in FluView or FluView Interactive for MMWR weeks 22 and 23. Data updates are expected to resume for week 24.



                Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                Surveillance Methods | FluView Interactive
                Influenza-Associated Pediatric Mortality


                One influenza-associated pediatric death occurring during the 2021-2022 season was reported to CDC during week 23. The death was associated with an influenza A(H3) virus and occurred during week 23.

                A total of 29 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                View Full Screen

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


                Additional National and International Influenza Surveillance Information


                FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                Additional influenza surveillance information from participating WHO member nations is available through
                FluNet and the Global Epidemiology Reports.

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

                Europe:
                The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                Public Health Agency of Canada:
                The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                Public Health England:
                The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                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.

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

                https://www.cdc.gov/flu/weekly/index.htm

                Comment


                • #53

                  Weekly U.S. Influenza Surveillance Report


                  Updated June 24, 2022
                  2021-2022 Influenza Season
                  Week 24 ending June 18, 2022


                  This abbreviated version of FluView will be published weekly throughout the summer The first full report of the 2022-2023 influenza season will include data for week 40 (week ending October 8, 2022) and will be published on Friday, October 14, 2022. FluView Interactive is updated weekly year round.

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

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

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

                  Clinical Laboratories


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

                  No. of specimens tested 55,035 2,813,522
                  No. of positive specimens (%) 1,402 (2.5%) 124,303 (4.4%)
                  Positive specimens by type
                  Influenza A 1,364 (97.3%) 122,486 (98.5%)
                  Influenza B 38 (2.7%) 1,817 (1.5%)

                  View Chart Data | View Full Screen Public Health Laboratories


                  The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
                  No. of specimens tested 6,558 880,606
                  No. of positive specimens 60 24,197
                  Positive specimens by type/subtype
                  Influenza A 57 (95.0%) 24,068 (99.5%)
                  (H1N1)pdm09 0 28 (0.1%)
                  H3N2 35 (100%) 18,806 (99.9%)
                  H3N2v 0 1 (<0.1%)
                  Subtyping not performed 22 5,233
                  Influenza B 3 (5.0%) 129 (0.5%)
                  Yamagata lineage 0 1 (2.4%)
                  Victoria lineage 0 40 (97.6%)
                  Lineage not performed 3 88



                  View Chart Data | View Full Screen

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


                  The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                  Outpatient Respiratory Illness Visits


                  Nationwide during week 24, 1.9% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                  * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                  View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                  More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                  During week 24, the percentage of visits for respiratory illness reported in ILINet was 8.8% among those 0-4 years, 3.1% among those 5-24 years, 1.5% among those 25-49 years, 1.0% among those 50-64 years and 0.8% among those 65 years and older.



                  * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                  View Chart Data | View Full Screen
                  Outpatient Respiratory Illness Activity Map


                  Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                  Week 24
                  (Week ending
                  Jun. 18, 2022)
                  Week 23
                  (Week ending
                  Jun. 11, 2022)
                  Week 24
                  (Week ending
                  Jun. 18, 2022)
                  Week 23
                  (Week ending
                  Jun. 11, 2022)
                  Very High 0 0 1 3
                  High 2 3 13 13
                  Moderate 1 1 11 25
                  Low 6 6 52 60
                  Minimal 43 45 531 554
                  Insufficient Data 3 0 321 274



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

                  Additional information about medically attended visits for ILI for current and past seasons:
                  Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                  Long-term Care Facility (LTCF) Surveillance


                  LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 24, 45 (0.3%) of 14,448 reporting LTCFs reported at least one influenza positive test among their residents.



                  View Chart Data | View Full Screen

                  Additional information about long-term care facility surveillance:
                  Surveillance Methods | Additional Data
                  Hospitalization Surveillance

                  FluSurv-NET


                  The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                  Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                  Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                  HHS Protect Hospitalization Surveillance


                  Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 24, 1,736 patients with laboratory-confirmed influenza were admitted to the hospital.



                  View Chart Data | View Full Screen

                  Additional HHS Protect hospitalization surveillance information:
                  Surveillance Methods | Additional Data
                  Mortality Surveillance

                  National Center for Health Statistics (NCHS) Mortality Surveillance


                  Starting June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system is undergoing a system-wide upgrade. Because of this upgrade period, certain NVSS surveillance datasets and reports will be paused temporarily, including those used to evaluate pneumonia, influenza, and COVID-19 deaths. NCHS mortality data will not be published in FluView or FluView Interactive for MMWR weeks 22, 23, or 24. It is expected to resume for MMWR week 25.



                  Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                  Surveillance Methods | FluView Interactive
                  Influenza-Associated Pediatric Mortality


                  One influenza-associated pediatric death occurring during the 2021-2022 season was reported to CDC during week 24. The death was associated with an influenza A virus for which no subtyping was performed and occurred during week 18 (the week ending May 7, 2022).

                  A total of 30 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                  View Full Screen

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


                  Additional National and International Influenza Surveillance Information


                  FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                  National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                  U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                  Additional influenza surveillance information from participating WHO member nations is available through
                  FluNet and the Global Epidemiology Reports.

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

                  Europe:
                  The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                  Public Health Agency of Canada:
                  The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                  Public Health England:
                  The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                  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.

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

                  https://www.cdc.gov/flu/weekly/index.htm

                  Comment


                  • #54
                    Weekly U.S. Influenza Surveillance Report


                    Updated July 1, 2022

                    2021-2022 Influenza Season for Week 25, ending June 25, 2021

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

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

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

                    Clinical Laboratories


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

                    No. of specimens tested 47,363 2,879,071
                    No. of positive specimens (%) 833 (1.8%) 125,645 (4.4%)
                    Positive specimens by type
                    Influenza A 816 (98.0%) 123,810 (98.5%)
                    Influenza B 17 (2.0%) 1,835 (1.5%)

                    View Chart Data | View Full Screen Public Health Laboratories


                    The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
                    No. of specimens tested 11,818 899,596
                    No. of positive specimens 63 24,670
                    Positive specimens by type/subtype
                    Influenza A 62 (98.4%) 24,540 (99.5%)
                    (H1N1)pdm09 0 25 (0.1%)
                    H3N2 45 (100%) 19,257 (99.9%)
                    H3N2v 0 1 (<0.1%)
                    Subtyping not performed 17 5,257
                    Influenza B 1 (1.6%) 130 (0.5%)
                    Yamagata lineage 0 1 (2.4%)
                    Victoria lineage 0 40 (97.6%)
                    Lineage not performed 1 89



                    View Chart Data | View Full Screen

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


                    The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                    Outpatient Respiratory Illness Visits


                    Nationwide during week 25, 1.8% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                    * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                    View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                    More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                    During week 25, the percentage of visits for respiratory illness reported in ILINet was 8.0% among those 0-4 years, 2.7% among those 5-24 years, 1.4% among those 25-49 years, 1.0% among those 50-64 years, and 0.8% among those 65 years and older.



                    * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                    View Chart Data | View Full Screen
                    Outpatient Respiratory Illness Activity Map


                    Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                    Week 25
                    (Week ending
                    Jun. 25, 2022)
                    Week 24
                    (Week ending
                    Jun. 18, 2022)
                    Week 25
                    (Week ending
                    Jun. 25, 2022)
                    Week 24
                    (Week ending
                    Jun. 18, 2022)
                    Very High 0 0 1 1
                    High 1 2 9 13
                    Moderate 2 1 15 14
                    Low 6 6 63 51
                    Minimal 45 44 525 567
                    Insufficient Data 1 2 316 283



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

                    Additional information about medically attended visits for ILI for current and past seasons:
                    Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                    Long-term Care Facility (LTCF) Surveillance


                    LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 25, 38 (0.3%) of 14,557 reporting LTCFs reported at least one influenza positive test among their residents.



                    View Chart Data | View Full Screen

                    Additional information about long-term care facility surveillance:
                    Surveillance Methods | Additional Data
                    Hospitalization Surveillance

                    FluSurv-NET


                    The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                    Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                    Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                    HHS Protect Hospitalization Surveillance


                    Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 25, 1,307 patients with laboratory-confirmed influenza were admitted to the hospital.



                    View Chart Data | View Full Screen

                    Additional HHS Protect hospitalization surveillance information:
                    Surveillance Methods | Additional Data
                    Mortality Surveillance

                    National Center for Health Statistics (NCHS) Mortality Surveillance


                    On June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system began a system-wide upgrade. Because of this upgrade period, certain NVSS surveillance datasets and reports were paused temporarily, including those used to evaluate pneumonia, influenza, and COVID-19 deaths. NCHS mortality data were not reported in FluView or FluView Interactive for MMWR weeks 22-24 due to this upgrade period and will not be reported for MMWR week 25 due to unplanned system maintenance. Regular reporting is expected to resume for week 26.



                    Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                    Surveillance Methods | FluView Interactive
                    Influenza-Associated Pediatric Mortality


                    One influenza-associated pediatric death occurring during the 2021-2022 season was reported to CDC during week 25. The death was associated with an influenza A virus for which no subtyping was performed and occurred during week 23 (the week ending June 11, 2022).

                    A total of 31 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                    View Full Screen

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


                    Additional National and International Influenza Surveillance Information


                    FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                    National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                    U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                    Additional influenza surveillance information from participating WHO member nations is available through
                    FluNet and the Global Epidemiology Reports.

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

                    Europe:
                    The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                    Public Health Agency of Canada:
                    The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                    Public Health England:
                    The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                    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.

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

                    https://www.cdc.gov/flu/weekly/index.htm

                    Comment


                    • #55
                      Weekly U.S. Influenza Surveillance Report


                      Updated July 8, 2022

                      2021-2022 Influenza Season for Week 26, ending July 2, 2022

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

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

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

                      Clinical Laboratories


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

                      No. of specimens tested 47,098 2,945,010
                      No. of positive specimens (%) 674 (1.4%) 126,675 (4.3%)
                      Positive specimens by type
                      Influenza A 656 (97.3%) 124,806 (98.5%)
                      Influenza B 18 (2.7%) 1,869 (1.5%)

                      View Chart Data | View Full Screen Public Health Laboratories


                      The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
                      No. of specimens tested 12,174 912,285
                      No. of positive specimens 44 24,810
                      Positive specimens by type/subtype
                      Influenza A 43 (97.7%) 24,679 (99.5%)
                      (H1N1)pdm09 0 25 (0.1%)
                      H3N2 20 (100%) 19,354 (99.9%)
                      H3N2v 0 1 (<0.1%)
                      Subtyping not performed 23 5,299
                      Influenza B 1 (2.3%) 131 (0.5%)
                      Yamagata lineage 0 1 (2.4%)
                      Victoria lineage 0 40 (97.6%)
                      Lineage not performed 1 90



                      View Chart Data | View Full Screen

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


                      The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                      Outpatient Respiratory Illness Visits


                      Nationwide during week 26, 1.7% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                      * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                      View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                      More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                      During week 26, the percentage of visits for respiratory illness reported in ILINet was 7.4% among those 0-4 years, 2.3% among those 5-24 years, 1.3% among those 25-49 years, 1.0% among those 50-64 years, and 0.8% among those 65 years and older.



                      * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                      View Chart Data | View Full Screen
                      Outpatient Respiratory Illness Activity Map


                      Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                      Week 26
                      (Week ending
                      Jul. 2, 2022)
                      Week 25
                      (Week ending
                      Jun. 25, 2022)
                      Week 26
                      (Week ending
                      Jul. 2, 2022)
                      Week 24
                      (Week ending
                      Jun. 25, 2022)
                      Very High 0 0 0 1
                      High 1 1 7 9
                      Moderate 2 3 19 16
                      Low 2 5 50 65
                      Minimal 47 46 559 562
                      Insufficient Data 3 0 294 276



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

                      Additional information about medically attended visits for ILI for current and past seasons:
                      Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                      Long-term Care Facility (LTCF) Surveillance


                      LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 26, 35 (0.2%) of 14,559 reporting LTCFs reported at least one influenza positive test among their residents.



                      View Chart Data | View Full Screen

                      Additional information about long-term care facility surveillance:
                      Surveillance Methods | Additional Data
                      Hospitalization Surveillance

                      FluSurv-NET


                      The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                      Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                      Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                      HHS Protect Hospitalization Surveillance


                      Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 26, 964 patients with laboratory-confirmed influenza were admitted to the hospital.



                      View Chart Data | View Full Screen

                      Additional HHS Protect hospitalization surveillance information:
                      Surveillance Methods | Additional Data
                      Mortality Surveillance

                      National Center for Health Statistics (NCHS) Mortality Surveillance


                      On June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system began a system-wide upgrade, which required a temporary suspension of routine NVSS surveillance reporting. The upgrade required all 2022 death records to be reprocessed into the system. As routine NVSS surveillance reporting resumes, users may temporarily observe lower death counts for prior weeks in 2022 as the backlog is reprocessed and reloaded into the system.

                      Based on NCHS mortality surveillance data available on July 7, 2022, 8.8% of the deaths that occurred during the week ending July 2, 2022 (week 26), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 5.8% for this week. Among the 1,449 PIC deaths reported for this week, 690 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and 12 listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



                      View Chart Data | View Full Screen

                      Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                      Surveillance Methods | FluView Interactive
                      Influenza-Associated Pediatric Mortality


                      One influenza-associated pediatric death occurring during the 2021-2022 season was reported to CDC during week 26. The death was associated with an influenza B virus with no lineage determined and occurred during week 25 (the week ending June 25, 2022).

                      A total of 32 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                      View Full Screen

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


                      Additional National and International Influenza Surveillance Information


                      FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                      National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                      U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                      Additional influenza surveillance information from participating WHO member nations is available through
                      FluNet and the Global Epidemiology Reports.

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

                      Europe:
                      The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                      Public Health Agency of Canada:
                      The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                      Public Health England:
                      The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                      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.

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

                      https://www.cdc.gov/flu/weekly/index.htm

                      Comment


                      • #56

                        Weekly U.S. Influenza Surveillance Report


                        Updated July 15, 2022

                        2021-2022 Influenza Season for Week 27, ending July 9, 2022

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

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

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

                        Clinical Laboratories


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

                        No. of specimens tested 43,645 3,089,585
                        No. of positive specimens (%) 323 (0.7%) 132,128 (4.3%)
                        Positive specimens by type
                        Influenza A 314 (97.2%) 130,185 (98.5%)
                        Influenza B 9 (2.8%) 1,943 (1.5%)

                        View Chart Data | View Full Screen Public Health Laboratories


                        The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
                        No. of specimens tested 17,494 945,727
                        No. of positive specimens 49 25,069
                        Positive specimens by type/subtype
                        Influenza A 48 (98.0%) 24,937 (99.5%)
                        (H1N1)pdm09 0 26 (0.1%)
                        H3N2 38 (100%) 19,623 (99.9%)
                        H3N2v 0 1 (<0.1%)
                        Subtyping not performed 10 5,287
                        Influenza B 1 (2.0%) 132 (0.5%)
                        Yamagata lineage 0 1 (2.4%)
                        Victoria lineage 0 40 (97.6%)
                        Lineage not performed 1 91



                        View Chart Data | View Full Screen

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


                        The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                        Outpatient Respiratory Illness Visits


                        Nationwide during week 27, 1.7% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                        * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                        View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                        More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                        During week 27, the percentage of visits for respiratory illness reported in ILINet was 7.3% among those 0-4 years, 2.3% among those 5-24 years, 1.3% among those 25-49 years, 1.0% among those 50-64 years, and 0.8% among those 65 years and older.



                        * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                        View Chart Data | View Full Screen
                        Outpatient Respiratory Illness Activity Map


                        Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                        Week 27
                        (Week ending
                        Jul. 9, 2022)
                        Week 26
                        (Week ending
                        Jul. 2, 2022)
                        Week 27
                        (Week ending
                        Jul. 9, 2022)
                        Week 26
                        (Week ending
                        Jul. 2, 2022)
                        Very High 0 0 0 1
                        High 1 1 7 7
                        Moderate 1 2 20 19
                        Low 4 2 61 53
                        Minimal 48 47 530 566
                        Insufficient Data 1 3 311 283



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

                        Additional information about medically attended visits for ILI for current and past seasons:
                        Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                        Long-term Care Facility (LTCF) Surveillance


                        LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 27, 23 (0.2%) of 14,541 reporting LTCFs reported at least one influenza positive test among their residents.



                        View Chart Data | View Full Screen

                        Additional information about long-term care facility surveillance:
                        Surveillance Methods | Additional Data
                        Hospitalization Surveillance

                        FluSurv-NET


                        The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                        Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                        Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                        HHS Protect Hospitalization Surveillance


                        Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 27, 751 patients with laboratory-confirmed influenza were admitted to the hospital.



                        View Chart Data | View Full Screen

                        Additional HHS Protect hospitalization surveillance information:
                        Surveillance Methods | Additional Data
                        Mortality Surveillance

                        National Center for Health Statistics (NCHS) Mortality Surveillance


                        On June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system began a system-wide upgrade, which required a temporary suspension of routine NVSS surveillance reporting. The upgrade required all 2022 death records to be reprocessed into the system. As routine NVSS surveillance reporting resumes, users may temporarily observe lower death counts for prior weeks in 2022 as the backlog is reprocessed and reloaded into the system.

                        Based on NCHS mortality surveillance data available on July 14, 2022, 8.8% of the deaths that occurred during the week ending July 9, 2022 (week 27), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 5.7% for this week. Among the 1,796 PIC deaths reported for this week, 876 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and 13 listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



                        View Chart Data | View Full Screen

                        Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                        Surveillance Methods | FluView Interactive
                        Influenza-Associated Pediatric Mortality


                        No influenza-associated pediatric deaths were reported to CDC during week 27.

                        A total of 32 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                        View Full Screen

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


                        Additional National and International Influenza Surveillance Information


                        FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                        National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                        U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                        Additional influenza surveillance information from participating WHO member nations is available through
                        FluNet and the Global Epidemiology Reports.

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

                        Europe:
                        The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                        Public Health Agency of Canada:
                        The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                        Public Health England:
                        The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                        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.

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

                        https://www.cdc.gov/flu/weekly/index.htm

                        Comment


                        • #57
                          Weekly U.S. Influenza Surveillance Report


                          Updated July 22, 2022

                          2021-2022 Influenza Season for Week 28, ending July 16, 2022

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

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

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

                          Clinical Laboratories


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

                          No. of specimens tested 42,188 3,147,400
                          No. of positive specimens (%) 276 (0.7%) 132,554 (4.2%)
                          Positive specimens by type
                          Influenza A 251 (90.9%) 130,560 (98.5%)
                          Influenza B 25 (9.1%) 1,994 (1.5%)

                          View Chart Data | View Full Screen Public Health Laboratories


                          The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
                          No. of specimens tested 12,048 962,877
                          No. of positive specimens 38 25,161
                          Positive specimens by type/subtype
                          Influenza A 37 (97.4%) 25,028 (99.5%)
                          (H1N1)pdm09 0 26 (0.1%)
                          H3N2 27 (100%) 19,778 (99.9%)
                          H3N2v 0 1 (<0.1%)
                          Subtyping not performed 10 5,223
                          Influenza B 1 (2.6%) 133 (0.5%)
                          Yamagata lineage 0 1 (2.4%)
                          Victoria lineage 0 40 (97.6%)
                          Lineage not performed 1 92



                          View Chart Data | View Full Screen

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


                          The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                          Outpatient Respiratory Illness Visits


                          Nationwide during week 28, 1.6% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                          * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                          View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                          More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                          During week 28, the percentage of visits for respiratory illness reported in ILINet was 6.5% among those 0-4 years, 2.1% among those 5-24 years, 1.3% among those 25-49 years, 1.0% among those 50-64 years, and 0.8% among those 65 years and older.



                          * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                          View Chart Data | View Full Screen
                          Outpatient Respiratory Illness Activity Map


                          Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                          Week 28
                          (Week ending
                          Jul. 16, 2022)
                          Week 27
                          (Week ending
                          Jul. 9, 2022)
                          Week 28
                          (Week ending
                          Jul. 16, 2022)
                          Week 27
                          (Week ending
                          Jul. 9, 2022)
                          Very High 0 0 0 1
                          High 1 0 9 7
                          Moderate 1 3 15 22
                          Low 2 4 53 63
                          Minimal 51 48 563 562
                          Insufficient Data 0 0 289 274



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

                          Additional information about medically attended visits for ILI for current and past seasons:
                          Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                          Long-term Care Facility (LTCF) Surveillance


                          LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 28, 33 (0.2%) of 14,507 reporting LTCFs reported at least one influenza positive test among their residents.



                          View Chart Data | View Full Screen

                          Additional information about long-term care facility surveillance:
                          Surveillance Methods | Additional Data
                          Hospitalization Surveillance

                          FluSurv-NET


                          The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                          Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                          Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                          HHS Protect Hospitalization Surveillance


                          Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 28, 722 patients with laboratory-confirmed influenza were admitted to the hospital.



                          View Chart Data | View Full Screen

                          Additional HHS Protect hospitalization surveillance information:
                          Surveillance Methods | Additional Data
                          Mortality Surveillance

                          National Center for Health Statistics (NCHS) Mortality Surveillance


                          On June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system began a system-wide upgrade, which required a temporary suspension of routine NVSS surveillance reporting. The upgrade required all 2022 death records to be reprocessed into the system. As routine NVSS surveillance reporting resumes, users may temporarily observe lower death counts for prior weeks in 2022 as the backlog is reprocessed and reloaded into the system.

                          Based on NCHS mortality surveillance data available on July 21, 2022, 9.5% of the deaths that occurred during the week ending July 16, 2022 (week 28), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 5.7% for this week. Among the 1,875 PIC deaths reported for this week, 958 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and four listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



                          View Chart Data | View Full Screen

                          Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                          Surveillance Methods | FluView Interactive
                          Influenza-Associated Pediatric Mortality


                          No influenza-associated pediatric deaths were reported to CDC during week 28.

                          A total of 32 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                          View Full Screen

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


                          Additional National and International Influenza Surveillance Information


                          FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                          National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                          U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                          Additional influenza surveillance information from participating WHO member nations is available through
                          FluNet and the Global Epidemiology Reports.

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

                          Europe:
                          The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                          Public Health Agency of Canada:
                          The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                          Public Health England:
                          The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                          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.

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

                          https://www.cdc.gov/flu/weekly/index.htm

                          Comment


                          • #58
                            Weekly U.S. Influenza Surveillance Report


                            Updated July 29, 2022

                            2021-2022 Influenza Season for Week 29, ending July 23, 2022

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

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

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

                            Clinical Laboratories


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

                            No. of specimens tested 44,445 3,210,352
                            No. of positive specimens (%) 322 (0.7%) 133,277 (4.2%)
                            Positive specimens by type
                            Influenza A 299 (92.9%) 131,237 (98.5%)
                            Influenza B 23 (7.1%) 2,040 (1.5%)

                            View Chart Data | View Full Screen Public Health Laboratories


                            The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included as they are not circulating influenza viruses.
                            No. of specimens tested 13,806 978,924
                            No. of positive specimens 25 25,264
                            Positive specimens by type/subtype
                            Influenza A 21 (84.0%) 25,127 (99.5%)
                            (H1N1)pdm09 0 26 (0.1%)
                            H3N2 11 (100%) 19,892 (99.9%)
                            H3N2v 0 1 (<0.1%)
                            Subtyping not performed 10 5,208
                            Influenza B 4 (16.0%) 137 (0.5%)
                            Yamagata lineage 0 1 (2.4%)
                            Victoria lineage 0 40 (97.6%)
                            Lineage not performed 4 96



                            View Chart Data | View Full Screen

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


                            The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                            Outpatient Respiratory Illness Visits


                            Nationwide during week 29, 1.6% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                            * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                            View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                            More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                            During week 29, the percentage of visits for respiratory illness reported in ILINet was 6.4% among those 0-4 years, 2.1% among those 5-24 years, 1.2% among those 25-49 years, 0.9% among those 50-64 years, and 0.8% among those 65 years and older.



                            * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                            View Chart Data | View Full Screen
                            Outpatient Respiratory Illness Activity Map


                            Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                            Week 29
                            (Week ending
                            Jul. 23, 2022)
                            Week 28
                            (Week ending
                            Jul. 16, 2022)
                            Week 29
                            (Week ending
                            Jul. 23, 2022)
                            Week 28
                            (Week ending
                            Jul. 16, 2022)
                            Very High 0 0 0 1
                            High 0 0 9 9
                            Moderate 1 1 17 16
                            Low 4 2 48 54
                            Minimal 50 52 577 575
                            Insufficient Data 0 0 278 274



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

                            Additional information about medically attended visits for ILI for current and past seasons:
                            Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                            Long-term Care Facility (LTCF) Surveillance


                            LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 29, 39 (0.3%) of 14,455 reporting LTCFs reported at least one influenza positive test among their residents.



                            View Chart Data | View Full Screen

                            Additional information about long-term care facility surveillance:
                            Surveillance Methods | Additional Data
                            Hospitalization Surveillance

                            FluSurv-NET


                            The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                            Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                            Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                            HHS Protect Hospitalization Surveillance


                            Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 29, 586 patients with laboratory-confirmed influenza were admitted to the hospital.



                            View Chart Data | View Full Screen

                            Additional HHS Protect hospitalization surveillance information:
                            Surveillance Methods | Additional Data
                            Mortality Surveillance

                            National Center for Health Statistics (NCHS) Mortality Surveillance


                            On June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system began a system-wide upgrade, which required a temporary suspension of routine NVSS surveillance reporting. The upgrade required all 2022 death records to be reprocessed into the system. As routine NVSS surveillance reporting resumes, users may temporarily observe lower death counts for prior weeks in 2022 as the backlog is reprocessed and reloaded into the system.

                            Based on NCHS mortality surveillance data available on July 28, 2022, 9.8% of the deaths that occurred during the week ending July 23, 2022 (week 29), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 5.6% for this week. Among the 2,050 PIC deaths reported for this week, 1,094 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and eight listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



                            View Chart Data | View Full Screen

                            Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                            Surveillance Methods | FluView Interactive
                            Influenza-Associated Pediatric Mortality


                            One influenza-associated pediatric death occurring during the 2021-2022 season was reported to CDC during week 29. The death was associated with an influenza A(H3) virus and occurred during week 52 (the week ending January 1, 2022).

                            A total of 33 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                            View Full Screen

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


                            Additional National and International Influenza Surveillance Information


                            FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                            National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                            U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                            Additional influenza surveillance information from participating WHO member nations is available through
                            FluNet and the Global Epidemiology Reports.

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

                            Europe:
                            The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                            Public Health Agency of Canada:
                            The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                            Public Health England:
                            The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                            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.

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

                            https://www.cdc.gov/flu/weekly/index.htm

                            Comment


                            • #59
                              Weekly U.S. Influenza Surveillance Report


                              Updated August 5, 2022

                              2021-2022 Influenza Season for Week 30, ending July 30, 2022

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

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

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

                              Clinical Laboratories


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

                              No. of specimens tested 34,963 3,255,594
                              No. of positive specimens (%) 166 (0.5%) 133,514 (4.1%)
                              Positive specimens by type
                              Influenza A 141 (84.9%) 131,433 (98.4%)
                              Influenza B 25 (15.1%) 2,081 (1.6%)

                              View Chart Data | View Full Screen Public Health Laboratories


                              The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included, as they are not circulating influenza viruses.
                              No. of specimens tested 11,985 992,138
                              No. of positive specimens 23 25,415
                              Positive specimens by type/subtype
                              Influenza A 20 (87.0%) 25,275 (99.5%)
                              (H1N1)pdm09 0 26 (0.1%)
                              H3N2 6 (100%) 20,016 (99.9%)
                              H3N2v 0 1 (<0.1%)
                              Subtyping not performed 14 5,232
                              Influenza B 3 (13.0%) 140 (0.6%)
                              Yamagata lineage 0 1 (2.4%)
                              Victoria lineage 0 40 (97.6%)
                              Lineage not performed 3 99



                              View Chart Data | View Full Screen

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


                              One human infection with a novel influenza A virus was reported by West Virginia. The patient was infected with an influenza A(H3N2) variant (A(H3N2)v) virus. The patient is a child < 18 years, was not hospitalized, and is recovering from their illness. An investigation by health officials showed that the patient participated in an agricultural fair and had direct contact with swine and that swine at this fair tested presumptively positive for influenza A. There have been additional reports of respiratory illness among people who attended the same fair; further investigation is ongoing. No person-to-person spread of this virus has been identified to date in this case.

                              When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant influenza virus.” These infections are relatively rare but happen sporadically. This is the first influenza A(H3N2)v virus identified in the United States during 2022.

                              Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be understood and appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza virus infection in humans, and guidance to interact safely with swine can be found at www.cdc.gov/flu/swineflu/index.htm. Additional information regarding human infections with novel influenza A viruses can be found at http://gis.cdc.gov/grasp/fluview/Novel_Influenza.html.
                              Outpatient Respiratory Illness Surveillance


                              The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                              Outpatient Respiratory Illness Visits


                              Nationwide during week 30, 1.6% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                              * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                              View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                              More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                              During week 30, the percentage of visits for respiratory illness reported in ILINet was 6.4% among those 0-4 years, 2.1% among those 5-24 years, 1.2% among those 25-49 years, 0.9% among those 50-64 years, and 0.8% among those 65 years and older.



                              * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                              View Chart Data | View Full Screen
                              Outpatient Respiratory Illness Activity Map


                              Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                              Week 30
                              (Week ending
                              Jul. 30, 2022)
                              Week 29
                              (Week ending
                              Jul. 23, 2022)
                              Week 30
                              (Week ending
                              Jul. 30, 2022)
                              Week 29
                              (Week ending
                              Jul. 23, 2022)
                              Very High 0 0 2 2
                              High 0 0 7 8
                              Moderate 2 1 18 16
                              Low 1 2 47 51
                              Minimal 52 52 564 585
                              Insufficient Data 0 0 291 267



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

                              Additional information about medically attended visits for ILI for current and past seasons:
                              Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                              Long-term Care Facility (LTCF) Surveillance


                              LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 30, 37 (0.3%) of 14,524 reporting LTCFs reported at least one influenza positive test among their residents.



                              View Chart Data | View Full Screen

                              Additional information about long-term care facility surveillance:
                              Surveillance Methods | Additional Data
                              Hospitalization Surveillance

                              FluSurv-NET


                              The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                              Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                              Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                              HHS Protect Hospitalization Surveillance


                              Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During week 30, 491 patients with laboratory-confirmed influenza were admitted to the hospital.



                              View Chart Data | View Full Screen

                              Additional HHS Protect hospitalization surveillance information:
                              Surveillance Methods | Additional Data
                              Mortality Surveillance

                              National Center for Health Statistics (NCHS) Mortality Surveillance


                              On June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system began a system-wide upgrade, which required a temporary suspension of routine NVSS surveillance reporting. The upgrade required all 2022 death records to be reprocessed into the system. As routine NVSS surveillance reporting resumes, users may temporarily observe lower death counts for prior weeks in 2022 as the backlog is reprocessed and reloaded into the system.

                              Based on NCHS mortality surveillance data available on August 4, 2022, 10.0% of the deaths that occurred during the week ending July 30, 2022 (week 30), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 5.6% for this week. Among the 2,009 PIC deaths reported for this week, 1,054 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and 10 listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



                              View Chart Data | View Full Screen

                              Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                              Surveillance Methods | FluView Interactive
                              Influenza-Associated Pediatric Mortality


                              No influenza-associated pediatric death occurring during the 2021-2022 season were reported to CDC during week 30.

                              A total of 33 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                              View Full Screen

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


                              Additional National and International Influenza Surveillance Information


                              FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                              National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                              U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                              Additional influenza surveillance information from participating WHO member nations is available through
                              FluNet and the Global Epidemiology Reports.

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

                              Europe:
                              The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                              Public Health Agency of Canada:
                              The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                              Public Health England:
                              The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                              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.

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

                              https://www.cdc.gov/flu/weekly/index.htm

                              Comment


                              • #60
                                Weekly U.S. Influenza Surveillance Report


                                Updated August 12, 2022

                                2021-2022 Influenza Season for Week 31, ending August 6, 2022

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

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

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

                                Clinical Laboratories


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

                                No. of specimens tested 34,645 3,308,468
                                No. of positive specimens (%) 153 (0.4%) 133,801 (4.0%)
                                Positive specimens by type
                                Influenza A 138 (90.2%) 131,699 (98.4%)
                                Influenza B 15 (9.8%) 2,102 (1.6%)

                                View Chart Data | View Full Screen Public Health Laboratories


                                The results of tests performed by public health laboratories nationwide are summarized below. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Data from public health laboratories are used to monitor the proportion of circulating viruses that belong to each influenza subtype/lineage. Viruses known to be associated with recent live attenuated influenza vaccine (LAIV) receipt or found upon further testing to be a vaccine virus are not included, as they are not circulating influenza viruses.
                                No. of specimens tested 12,394 1,006,839
                                No. of positive specimens 25 25,507
                                Positive specimens by type/subtype
                                Influenza A 23 (92.0%) 25,365 (99.4%)
                                (H1N1)pdm09 0 26 (0.1%)
                                H3N2 15 (83.3%) 20,092 (99.9%)
                                H3N2v 3 (16.7) 4 (<0.1%)
                                Subtyping not performed 5 5,243
                                Influenza B 2 (8.0%) 142 (0.6%)
                                Yamagata lineage 0 1 (2.4%)
                                Victoria lineage 0 40 (97.6%)
                                Lineage not performed 2 101



                                View Chart Data | View Full Screen

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


                                Two human infections with a novel influenza A virus were reported by West Virginia. The patients were infected with an influenza A(H3N2) variant (A(H3N2)v) virus. Both patients are <18 years of age, were not hospitalized, and have recovered from their illness. An investigation by health officials showed that both patients attended an agricultural fair and that swine at this fair tested positive for swine influenza A(H3N2). No person-to-person spread of this virus has been confirmed to date. This is the third patient infected with an H3N2v virus reported from West Virginia in the past 2 weeks; all three attended the same agricultural fair prior to illness onset.

                                When an influenza virus that normally circulates in swine (but not people) is detected in a person, it is called a “variant influenza virus.” Most human infections with variant influenza viruses occur following close proximity to swine, but human-to-human transmission has occurred previously. It is important to note that in most cases, variant influenza viruses have not shown the ability to spread easily and sustainably from person to person.

                                Early identification and investigation of human infections with novel influenza A viruses are critical so that the risk of infection can be understood and appropriate public health measures can be taken. Additional information on influenza in swine, variant influenza virus infection in humans, and guidance to interact safely with swine can be found at www.cdc.gov/flu/swineflu/index.htm. Additional information regarding human infections with novel influenza A viruses can be found at http://gis.cdc.gov/grasp/fluview/Novel_Influenza.html.
                                Outpatient Respiratory Illness Surveillance


                                The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) monitors outpatient visits for influenza-like illness [ILI (fever plus cough or sore throat)], not laboratory-confirmed influenza, and will therefore capture respiratory illness visits due to infection with any pathogen that can present with similar symptoms, including influenza, SARS-CoV-2, and RSV. Due to the COVID-19 pandemic, health care-seeking behaviors have changed, and people may be accessing the health care system in alternative settings not captured as a part of ILINet or at a different point in their illness than they might have before the pandemic. Therefore, it is important to evaluate syndromic surveillance data, including that from ILINet, in the context of other sources of surveillance data to obtain a complete and accurate picture of influenza, SARS-CoV-2, and other respiratory virus activity. CDC is tracking the COVID-19 pandemic in a weekly publication called COVID Data Tracker Weekly Review. Information about other respiratory virus activity can be found on CDC’s National Respiratory and Enteric Virus Surveillance System (NREVSS) website.
                                Outpatient Respiratory Illness Visits


                                Nationwide during week 31, 1.5% of patient visits reported through ILINet were due to respiratory illness that included fever plus a cough or sore throat, also referred to as ILI. Multiple respiratory viruses are co-circulating, and the relative contribution of influenza virus infection to ILI varies by location.



                                * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”


                                View Chart Data (current season only) | View Full ScreenOutpatient Respiratory Illness Visits by Age Group


                                More than 70% of ILINet participants provide both the number of patient visits for respiratory illness and the total number of patient visits for the week broken out by age group. Data from this subset of providers are used to calculate the percentages of patient visits for respiratory illness by age group.

                                During week 31, the percentage of visits for respiratory illness reported in ILINet was 6.1% among those 0-4 years, 1.9% among those 5-24 years, 1.1% among those 25-49 years, 0.8% among those 50-64 years, and 0.7% among those 65 years and older.



                                * Effective October 3, 2021 (week 40), the ILI definition (fever plus cough or sore throat) no longer includes “without a known cause other than influenza.”

                                View Chart Data | View Full Screen
                                Outpatient Respiratory Illness Activity Map


                                Data collected in ILINet are used to produce a measure of ILI activity* by state/jurisdiction and Core Based Statistical Areas (CBSA).
                                Week 31
                                (Week ending
                                Aug. 6, 2022)
                                Week 30
                                (Week ending
                                Jul. 30, 2022)
                                Week 31
                                (Week ending
                                Aug. 6, 2022)
                                Week 30
                                (Week ending
                                Jul. 30, 2022)
                                Very High 0 0 0 2
                                High 0 0 4 7
                                Moderate 1 2 10 18
                                Low 1 1 53 48
                                Minimal 53 52 582 570
                                Insufficient Data 0 0 280 284



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

                                Additional information about medically attended visits for ILI for current and past seasons:
                                Surveillance Methods | FluView Interactive: National, Regional, and State Data or ILI Activity Map
                                Long-term Care Facility (LTCF) Surveillance


                                LTCFs (e.g., nursing homes/skilled nursing, long-term care for the developmentally disabled, and assisted living facilities) from all 50 states and U.S. territories report data on influenza virus infections among residents through the National Healthcare Safety Network (NHSN) Long-term Care Facility Component. During week 31, 40 (0.3%) of 14,636 reporting LTCFs reported at least one influenza positive test among their residents.



                                View Chart Data | View Full Screen

                                Additional information about long-term care facility surveillance:
                                Surveillance Methods | Additional Data
                                Hospitalization Surveillance

                                FluSurv-NET


                                The Influenza Hospitalization Surveillance Network (FluSurv-NET) conducts population-based surveillance for laboratory-confirmed influenza-related hospitalizations in select counties in 14 states and represents approximately 9% of the U.S. population. FluSurv-NET hospitalization data are preliminary. Patients admitted for laboratory-confirmed influenza-related hospitalization after June 11, 2022, will not be included in FluSurv-NET for the 2021-2022 season. Data on patients admitted through June 11, 2022, will continue to be updated as additional information is received.

                                Additional FluSurv-NET hospitalization surveillance information for current and past seasons and additional age groups:
                                Surveillance Methods |FluView Interactive: Rates by Age, Sex, and Race/Ethnicity or Data on Patient Characteristics
                                HHS Protect Hospitalization Surveillance


                                Hospitals report to HHS Protect the number of patients admitted with laboratory-confirmed influenza. During 31, 506 patients with laboratory-confirmed influenza were admitted to the hospital.



                                View Chart Data | View Full Screen

                                Additional HHS Protect hospitalization surveillance information:
                                Surveillance Methods | Additional Data
                                Mortality Surveillance

                                National Center for Health Statistics (NCHS) Mortality Surveillance


                                On June 6, 2022, the National Vital Statistics System (NVSS) cause of death coding system began a system-wide upgrade, which required a temporary suspension of routine NVSS surveillance reporting. The upgrade required all 2022 death records to be reprocessed into the system. As routine NVSS surveillance reporting resumes, users may temporarily observe lower death counts for prior weeks in 2022 as the backlog is reprocessed and reloaded into the system.

                                Based on NCHS mortality surveillance data available on August 11, 2022, 10.0% of the deaths that occurred during the week ending August 6, 2022 (week 31), were due to pneumonia, influenza, and/or COVID-19 (PIC). This percentage is above the epidemic threshold of 5.5% for this week. Among the 2,226 PIC deaths reported for this week, 1,207 had COVID-19 listed as an underlying or contributing cause of death on the death certificate, and 4 listed influenza, indicating that current PIC mortality is due primarily to COVID-19 and not influenza. The data presented are preliminary and may change as more data are received and processed.



                                View Chart Data | View Full Screen

                                Additional pneumonia, influenza and COVID-19 mortality surveillance information for current and past seasons:
                                Surveillance Methods | FluView Interactive
                                Influenza-Associated Pediatric Mortality


                                No influenza-associated pediatric death occurring during the 2021-2022 season were reported to CDC during week 31.

                                A total of 33 influenza-associated pediatric deaths occurring during the 2021-2022 season have been reported to CDC.


                                View Full Screen

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


                                Additional National and International Influenza Surveillance Information


                                FluView Interactive: FluView includes enhanced web-based interactive applications that can provide dynamic visuals of the influenza data collected and analyzed by CDC. These FluView Interactive applications allow people to create customized, visual interpretations of influenza data, as well as make comparisons across flu seasons, regions, age groups and a variety of other demographics.

                                National Institute for Occupational Safety and Health: Monthly surveillance data on the prevalence of health-related workplace absenteeism among full-time workers in the United States are available from NIOSH.

                                U.S. State and local influenza surveillance: Select a jurisdiction below to access the latest local influenza information. World Health Organization:
                                Additional influenza surveillance information from participating WHO member nations is available through
                                FluNet and the Global Epidemiology Reports.

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

                                Europe:
                                The most up-to-date influenza information from Europe is available from WHO/Europe and the European Centre for Disease Prevention and Control.

                                Public Health Agency of Canada:
                                The most up-to-date influenza information from Canada is available in Canada’s weekly FluWatch report.

                                Public Health England:
                                The most up-to-date influenza information from the United Kingdom is available from Public Health England.

                                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.

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

                                https://www.cdc.gov/flu/weekly/index.htm

                                Comment

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