H1N1 Virus (Swine Flu)

2009 H1N1 Flu: Situation Update, January 22, 2010

Atlanta, GA–(ENEWSPF)–January 22, 2010.

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 January 10-16, 2010, all key indicators, except for one, declined compared to the previous week. 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. Visits to doctors for ILI are low in 9 of the 10 U.S. regions. Region 9 had a small decrease in visits to doctors for ILI, but activity is still elevated.
  • Overall cumulative hospitalization rates for the 2009-10 influenza season have leveled off in all age groups and very few 2009 H1N1-laboratory confirmed hospitalizations were reported by states during the week ending January 16.
  • The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report increased over the previous week and is higher than expected for this time of year. This increase in P&I is thought to result from an increase in reports of pneumonia-associated deaths in older people. These deaths are not necessarily related to flu illness. In addition, another nine flu-related pediatric deaths were reported this week: three of these deaths were associated with laboratory confirmed 2009 H1N1, four were associated with an influenza A virus for which the subtype was undetermined, one was associated with an influenza A (H3) virus infection, and one was associated with an influenza B virus infection.  The influenza A (H3) and B deaths reported this week occurred during the 2008-09 influenza season, bringing the total number of reported pediatric deaths that season to 132. Since April 2009, CDC has received reports of 307 laboratory-confirmed pediatric deaths: 258 due to 2009 H1N1, 47 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.
  • No states reported widespread influenza activity.  Seven states continue to report regional influenza activity. They are: Alabama, Georgia, Maine, Nevada, New Jersey, South Carolina, 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 2009 to January 16, 2010
Posted January 22, 2010, 11:00 AM ET
Data reported to CDC by January 19, 2010, 12:00 AM ET
Cases Defined by
Influenza Laboratory-Tests** 38,989 1,812

*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 January 22, 2010 (Updated Weekly)
Data reported to CDC by January 16, 2010
Date Reported
Laboratory-Confirmed 2009 H1N1 Influenza Pediatric Deaths
Laboratory-Confirmed Influenza A Subtype Unknown Pediatric Deaths
This Week  (Week 2, January 10 to January 16, 2010) 3 4 2 9
Since August 30, 2009 198 44 1 243
Cumulative since April 26, 2009 258 47 2 307

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