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2009 H1N1 Flu Situation Update
September 18, 2009, 5:30 PM ET

This website is archived for historical purposes and is no longer being maintained or updated. For updated information on the current flu season, see the CDC Seasonal Flu website.

Map: Weekly Influenza Activity Estimates Reported by State and Territorial Epidemiologists
(Activity levels indicate geographic spread of both seasonal and 2009 influenza A [H1N1] viruses)
(Posted September 18, 2009, 5:30 PM ET, for Week Ending September 12, 2009)

FluView, Week Ending September 12, 2009. Weekly Influenza Surveillance Report Prepared by the Influenza Division. Weekly Influenza Activity Estimate Reported by State and Territorial Epidemiologists. Select this link for more detailed data.

For more details about the data in the map above, see the FluView Surveillance Report for the week ending September 12, 2009. For information about how this map is updated, see Questions & Answers About CDC's Online Reporting.

Percentage of Visits for Influenza-like Illness (ILI) Reported by the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet), National Summary 2008-2009 and Previous Two Seasons
(Posted September 18, 2009, 5:30 PM ET, for Week Ending September 12, 2009)

Graph of U.S. patient visits reported for Influenza-like Illness (ILI) for week ending September 12, 2009.

 

U.S. Influenza and Pneumonia-Associated Hospitalizations
and Deaths from August 30 – September 12, 2009
Posted September 18, 2009, 11:00 AM ET
Data reported to CDC by September 15, 2009, 12:00 AM ET
Cases Defined by
Hospitalizations
Deaths
Influenza and Pneumonia Syndrome* 3,534 291
Influenza Laboratory-Tests** 1,035 73

*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.

This table is based on data from a new influenza and pneumonia hospitalizations and deaths web-based reporting system that will be used to monitor trends in activity. This is the second week of data from this new system and reflects reports by 39 of 56 jurisdictions this week. The table shows aggregate reports of all influenza and pneumonia-associated 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.

 
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