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Situation Update: Summary of Weekly FluView Report

FluView Activity Update (Key Flu Indicators)

According to this week’s FluView report, seasonal influenza activity is increasing in the United States. During week 45 (the week ending November 11, 2017), several flu activity indicators were higher than is typically seen for this time of year. Nine U.S. states, Puerto Rico and Guam reported regional flu activity and 13 states reported local influenza activity. Flu vaccine is the best available way to protect against influenza. CDC recommends that everyone 6 months and older get an injectable flu vaccine as soon as possible. Below is a summary of the key flu indicators for the week ending November 11, 2017:

  • Influenza-like Illness Surveillance: For the week ending November 11, the proportion of people seeing their health care provider for influenza-like illness (ILI) was 1.9% and is below the national baseline of 2.2%. All 10 regions reported a proportion of outpatient visits for ILI below their region-specific baseline levels.
  • Influenza-like Illness State Activity Indicator Map: One state experienced high ILI activity (Louisiana). Two states experienced moderate ILI activity (Georgia and Mississippi). Six states (Alabama, Hawaii, Nebraska, South Carolina, South Dakota and Wyoming) experienced low ILI activity. New York City, the District of Columbia, Puerto Rico and 41 states experienced minimal ILI activity (Alaska, Arizona, Arkansas, California, Colorado, Connecticut, Delaware, Florida, Idaho, Illinois, Indiana, Iowa, Kansas, Kentucky, Maine, Maryland, Massachusetts, Michigan, Minnesota, Missouri, Montana, Nevada, New Hampshire, New Jersey, New Mexico, New York, North Carolina, North Dakota, Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, and Wisconsin).
  • Geographic Spread of Influenza Viruses: Regional influenza activity was reported by Guam, Puerto Rico and nine states (Arkansas, California, Georgia, Louisiana, Massachusetts, Mississippi, Oklahoma, South Carolina, and Washington). Local influenza activity was reported by 13 states (Alaska, Arizona, Colorado, Connecticut, Kentucky, Maine, Maryland, New Mexico, Ohio, Oregon, Pennsylvania, Texas, and Wisconsin). Sporadic activity was reported by the U.S. Virgin Islands and 26 states (Delaware, Florida, Hawaii, Idaho, Illinois, Indiana, Iowa, Kansas, Michigan, Minnesota, Missouri, Montana, Nebraska, Nevada, New Hampshire, New Jersey, New York, North Carolina, North Dakota, Rhode Island, South Dakota, Tennessee, Utah, Vermont, Virginia, and Wyoming). No activity was reported by the District of Columbia and two states (Alabama and West Virginia). Geographic spread data show how many areas within a state or territory are seeing flu activity.
    o Additional data are available at:
  • Flu-Associated Hospitalizations: Reporting of influenza-associated hospitalization data from the Influenza Hospitalization Surveillance Network (FluSurv-NET) for the 2017-2018 influenza season will begin later this season.
  • Mortality Surveillance:
    • The proportion of deaths attributed to pneumonia and influenza (P&I) was 5.9% for the week ending October 28, 2017 (week 43). This percentage is below the epidemic threshold of 6.3% for week 43 in the National Center for Health Statistics (NCHS) Mortality Surveillance System.
    • Region and state-specific data are available at https://gis.cdc.gov/grasp/fluview/mortality.html.
  • Pediatric Deaths:
    • No influenza-associated pediatric deaths were reported to CDC during the week ending November 11.
    • One influenza-associated pediatric death for the 2017-2018 season has been reported to CDC.
    • Additional information on pediatric deaths is available on FluView Interactive at: https://gis.cdc.gov/GRASP/Fluview/PedFluDeath.html
  • Laboratory Data:
    • Nationally, the percentage of respiratory specimens testing positive for influenza viruses in clinical laboratories during the week ending November 11 was 4.4%.
    • Regionally, the three week average percent of specimens testing positive for influenza in clinical laboratories ranged from 0.6% to 6.9%.
    • During the week ending November 11, of the 677 (4.4%) influenza-positive tests reported to CDC by clinical laboratories, 507 (74.9%) were influenza A viruses and 170 (25.1%) were influenza B viruses.
    • The most frequently identified influenza virus type reported by public health laboratories was influenza A virus.
    • During the week ending November 11, 154 (89.0%) of the 173 influenza-positive tests reported to CDC by public health laboratories were influenza A viruses and 19 (11.0%) were influenza B viruses. Of the 147 influenza A viruses that were subtyped, 135 (91.8%) were H3N2 viruses and 12 (8.2%) were (H1N1)pdm09 viruses.
    • The majority of the influenza viruses collected from the United States during May 21 through November 11, 2017 were characterized antigenically and genetically as being similar to the cell-grown reference viruses representing the 2017–18 Northern Hemisphere influenza vaccine viruses.
    • None of the influenza viruses tested from May 21-November 11, 2017 were found to be resistant to antiviral medications (i.e. oseltamivir, zanamivir, or peramivir).

FluView is available – and past issues are archived – on the CDC website.

Note: Delays in reporting may mean that data changes over time. The most up to date data for all weeks during the 2017-2018 season can be found on the current FluView and FluView Interactive.

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