H1N1 Virus (Swine Flu)

2009 H1N1 Flu: Situation Update, December 11, 2009

Atlanta, GA–(ENEWSPF)–December 11, 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 November 29-December 5, 2009, influenza activity decreased over the previous week across all key indicators except for deaths, but most indicators remain higher than normal for this time of year. Below is a summary of the most recent key indicators:

  • Visits to doctors for influenza-like illness (ILI) nationally decreased again this week over last week. This is the sixth consecutive week of national decreases in ILI after four consecutive weeks of sharp increases. While ILI has declined, visits to doctors for influenza-like illness remain elevated nationally.
  • Influenza hospitalization rates have decreased across all age groups but remain higher than expected for this time of year. Though declining, hospitalization rates continue to be highest in children 0-4 years old.
  • The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report increased over the previous week and has been higher than expected for ten consecutive weeks. In addition, 16 flu-related pediatric deaths were reported this week: 13 of these deaths were associated with laboratory confirmed 2009 H1N1, 2 were associated with influenza A viruses that were not subtyped and one was associated with a seasonal influenza B virus. Since April 2009, CDC has received reports of 267 laboratory-confirmed pediatric deaths: 224 due to 2009 H1N1, 41 pediatric deaths that were laboratory confirmed as influenza, but the flu virus subtype was not determined, and two pediatric deaths 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. The increase in the proportion of deaths as other indicators are going down is not surprising as the occurrence and reporting of deaths usually lags behind that of other indicators.
  • Fourteen states are reporting widespread influenza activity; a decline of 11 states from last week. They are: Alabama, Alaska, Arizona, California, Connecticut, Delaware, Kentucky, Maine, New Hampshire, New Jersey, New York, Rhode Island, Vermont, 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.

U.S. Laboratory Confirmed Influenza-Associated Hospitalizations
and Deaths from August 30 to December 5, 2009
Posted December 11, 2009, 11:00 AM ET
Data reported to CDC by December 8, 2009, 12:00 AM ET
Cases Defined by
Influenza Laboratory-Tests** 33,490 1,445

*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 each Friday 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 11, 2009 (Updated each Friday)
Data reported to CDC by December 5, 2009
Date Reported
Laboratory-Confirmed 2009 H1N1 Influenza Pediatric Deaths
Laboratory-Confirmed Influenza A Subtype Unknown Pediatric Deaths
This Week  (Week 48, November 29-December 5, 2009) 13 2 1 16
Since August 30, 2009 165 38 1 204
Cumulative since April 26, 2009 224 41 2 267

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