H1N1 Virus (Swine Flu)

H1N1 Flu: Situation Update, May 21, 2010

Atlanta, GA–(ENEWSPF)–May 21, 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 May 9-May 15, 2010, nationally all key flu indicators are low. Activity levels at this time are similar to what is usually seen during the U.S. summer months. Below is a summary of the most recent key indicators:

  • Visits to doctors for influenza-like illness (ILI) decreased from last week, and are low nationally, with all 10 U.S. regions reporting ILI below region-specific baseline.
  • Laboratory-confirmed hospitalizations rates have leveled off.
  • The proportion of deaths attributed to pneumonia and influenza (P&I) based on the 122 Cities Report remained about the same as last week. No pediatric deaths were associated with flu were reported this week. Since April 2009, CDC has received reports of 338 flu laboratory-confirmed pediatric deaths: 282 due to 2009 H1N1, 53 pediatric deaths that were laboratory confirmed as influenza A, but the flu virus subtype was not determined, and three 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 or regional influenza activity. This is the fifth consecutive week that no states reported widespread or regional flu activity. Most states are reporting no activity or sporadic activity.
  • The majority 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 April 3, 2010

Posted April 9, 2010, 11:00 AM ET
Data reported to CDC by April 6, 2010, 12:00 AM ET

As of April 16, 2010, the Aggregate Hospitalizations and Deaths Reporting Activity (AHDRA) has concluded for the 2009-2010 flu season. The AHDRA surveillance system was created specifically in response to the 2009 H1N1 pandemic, and the system will be maintained for quick implementation in the event of another flu pandemic. CDC will continue to track hospitalizations and deaths through its traditional seasonal flu surveillance systems during the 2010-2011 season. Pneumonia and influenza-related deaths in adults and children will be tracked through the 122 Cities Mortality Reporting System. Laboratory confirmed, flu-related deaths in children will continue to be tracked through the Influenza-associated Pediatric Mortality Surveillance system. Laboratory confirmed, flu-related hospitalizations in adults and children will be tracked through the Emerging Infections Program (EIP).

Cases Defined by
Influenza Laboratory-Tests** 41,821 2,117

*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 OrganizationExternal Web Site Icon

**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 May 21, 2010 (Updated Weekly)
Data reported to CDC by May 15, 2010
Date Reported
Laboratory-Confirmed 2009 H1N1 Influenza Pediatric Deaths
Laboratory-Confirmed Influenza A Subtype Unknown Pediatric Deaths
This Week (Week 19, May 9 – May 15, 2010) 0 0 0 0
Since August 30, 2009 222 50 1 273
Cumulative since April 26, 2009 282 53 3 338

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