FluView Week 45

# 4055

The CDC has posted FluView for week 45, ending November 14th, 2009. The level of activity we are seeing has decreased somewhat from the past couple of weeks, but is still much higher than normally seen this time of year.

P&I (pneumonia & Influenza) deaths remain above the epidemic level for this time of year, and 21 pediatric influenza-related deaths were added last week.

I’ve excerpted some of the data and graphs below, but follow the link to read it in its entirety.

Synopsis:

During week 45 (November 8-14, 2009), influenza activity decreased slightly in the U.S.

3,106 (28.8%) specimens tested by U.S. World Health Organization (WHO) and National Respiratory and Enteric Virus Surveillance System (NREVSS) collaborating laboratories and reported to CDC/Influenza Division were positive for influenza.

Over 99% of all subtyped influenza A viruses being reported to CDC were 2009 influenza A (H1N1) viruses.

The proportion of deaths attributed to pneumonia and influenza (P&I) was above the epidemic threshold for the seventh consecutive week.

Twenty-one influenza-associated pediatric deaths were reported. Fifteen of these deaths were associated with 2009 influenza A (H1N1) virus infection, and six were associated with an influenza A virus for which the subtype was undetermined.

The proportion of outpatient visits for influenza-like illness (ILI) was 5.5% which is above the national baseline of 2.3%. All 10 regions reported ILI above region-specific baseline levels.

Forty-three states reported geographically widespread influenza activity, Puerto Rico and seven states reported regional influenza activity, the District of Columbia reported local influenza activity, and Guam and the U.S. Virgin Islands reported sporadic influenza activity.

U.S. Virologic Surveillance:

WHO and NREVSS collaborating laboratories located in all 50 states and Washington D.C., report to CDC the number of respiratory specimens tested for influenza and the number positive by influenza type and subtype. The results of tests performed during the current week are summarized in the table below.

During week 45, seasonal influenza A (H1N1) and influenza B viruses co-circulated at low levels with 2009 influenza A (H1N1) viruses. Over 99% of all subtyped influenza A viruses reported to CDC this week were 2009 influenza A (H1N1) viruses.

Pneumonia and Influenza (P&I) Mortality Surveillance

During week 45, 7.5% of all deaths reported through the 122-Cities Mortality Reporting System were due to P&I. This percentage was above the epidemic threshold of 6.9% for week 45. Including week 45, P&I mortality has been above threshold for seven consecutive weeks.

Influenza-Associated Pediatric Mortality

Twenty-one influenza-associated pediatric deaths were reported to CDC during week 45 (Arizona [2], Colorado [3], Georgia [2], Louisiana [2], Minnesota, Mississippi, New York, New York City, Ohio, Oklahoma, Oregon [2], Texas, Virginia, Washington, and Wisconsin). Fifteen of these deaths were associated with 2009 influenza A (H1N1) virus infection, and six were associated with an influenza A virus for which the subtype is undetermined. The deaths reported during week 45 occurred between September 20 and November 14, 2009.

Since August 30, 2009, CDC has received 138 reports of influenza-associated pediatric deaths that occurred during the current influenza season (24 deaths in children less than 2 years old, 16 deaths in children 2-4 years old, 50 deaths in children 5-11 years old, and 48 deaths in children 12-17 years old). One hundred thirteen (82%) of the138 deaths were due to 2009 influenza A (H1N1) virus infections, and the remaining 25 were associated with influenza A virus for which the subtype is undetermined. A total of 171 deaths in children associated with 2009 influenza A (H1N1) virus infection have been reported to CDC.