H1N1 Virus (Swine Flu)

2009 H1N1 Flu: Situation Update, December 31, 2009

Atlanta, GA–(ENEWSPF)–December 31, 2009.

Each week CDC analyzes information about influenza disease activity in the United States and publishes findings of key flu indicators in a report called FluView. During the week of December 20-26, 2009, certain key indicators decreased, others increased, and still others remained the same compared to the previous week. Below is a summary of the most recent key indicators:

  • Visits to doctors for influenza-like illness (ILI) nationally increased slightly this week over last week. This is the first increase in this indicator after eight consecutive weeks of national decreases.  The increase in the percentage of visits to doctors for ILI during this is likely influenced by fewer people going to the doctor for routine health care visits during the holiday season, as has occurred during previous seasons.
  • Overall hospitalization rates for this season were unchanged from the previous week in all age groups.
  • The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report increased over the previous week and is now back above the epidemic threshold after dipping below it  last week for the first time in 11 weeks. (The epidemic threshold is the point at which the observed proportion of deaths attributed to pneumonia or influenza is significantly higher than would be expected at that time of the year in the absence of substantial influenza-related mortality.)
  • In addition, four flu-related pediatric deaths were reported this week compared to 9 reported last week: two of these deaths reported this week were associated with laboratory confirmed 2009 H1N1, and two were associated with  influenza A viruses that were not subtyped. Since April 2009, CDC has received reports of 289 laboratory-confirmed pediatric deaths: 243 due to 2009 H1N1, 44 pediatric deaths that were laboratory confirmed as influenza, but the flu virus subtype was not determined, and two pediatric deaths that were associated with seasonal influenza viruses. (Laboratory-confirmed deaths are thought to represent an undercount of the actual number. CDC has provided estimates about the number of 2009 H1N1 cases and related hospitalizations and deaths.
  • Four states are reporting widespread influenza activity; a decline of three states from last week. They are: Delaware, Maine, New Jersey and Virginia.
  • Almost all of the influenza viruses identified so far continue to be 2009 H1N1 influenza A viruses. These viruses remain similar to the virus chosen for the 2009 H1N1 vaccine, and remain susceptible to the antiviral drugs oseltamivir and zanamivir with rare exception.
  • *All data are preliminary and may change as more reports are received.

    Laboratory Confirmed Influenza-Associated Hospitalizations
    and Deaths from August 30 to December 26, 2009
    Posted December 31, 2009, 1:30 PM ET
    Data reported to CDC by December 29, 2009, 12:00 AM ET
    Cases Defined by
    Influenza Laboratory-Tests** 37,090 1,697

    *Reports can be based on syndromic, admission or discharge data, or a combination of data elements that could include laboratory-confirmed and influenza-like illness hospitalizations.

    *Laboratory confirmation includes any positive influenza test (rapid influenza tests, RT-PCR, DFA, IFA, or culture), whether or not typing was done.

    The table shows aggregate reports of all laboratory confirmed influenza hospitalizations and deaths (including 2009 H1N1 and seasonal flu) since August 30, 2009 received by CDC from U.S. states and territories**. This table will be updated weekly at 11 a.m. For the 2009-2010 influenza season, states are reporting based on new case definitions for hospitalizations and deaths effective August 30, 2009.

    CDC will continue to use its traditional surveillance systems to track the progress of the 2009-2010 influenza season. For more information about influenza surveillance, including reporting of influenza-associated hospitalizations and deaths, see Questions and Answers: Monitoring Influenza Activity, Including 2009 H1N1.

    The number of 2009 H1N1 hospitalizations and deaths reported to CDC from April – August 2009 is available on the Past Situation Updates page.

    For state level information, refer to state health departments.

    International Human Cases of 2009 H1N1 Flu Infection
    See: World Health Organization

    **States report weekly to CDC either 1) laboratory-confirmed influenza hospitalizations and deaths or 2) pneumonia and influenza syndrome-based cases of hospitalization and death resulting from all types or subtypes of influenza. Although only the laboratory confirmed cases are included in this report, CDC continues to analyze data both from laboratory confirmed and syndromic hospitalizations and deaths.

    U.S. Influenza-associated Pediatric Mortality
    Posted December 31, 2009 (Updated Weekly)
    Data reported to CDC by December 26, 2009
    Date Reported
    Laboratory-Confirmed 2009 H1N1 Influenza Pediatric Deaths
    Laboratory-Confirmed Influenza A Subtype Unknown Pediatric Deaths
    This Week  (Week 51, December 20-26, 2009) 2 2 0 4
    Since August 30, 2009 183 41 1 225
    Cumulative since April 26, 2009 243 44 2 289

    This table is based on data reported to CDC through the Influenza-Associated Pediatric Mortality Surveillance System. Influenza-associated deaths in children (persons less than 18 years) was added as nationally notifiable condition in 2004.

    For more information about influenza-associated pediatric mortality, see FluView.


    Source: cdc.gov