USA FluView Reports - Week 48 (2009) - Week 20 (2010)
"Synopsis:
During week 48 (November 29-December 5, 2009), influenza activity continued to decrease in the U.S
* 478 (8.9%) 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 tenth consecutive week.
* Sixteen influenza-associated pediatric deaths were reported. Thirteen of these deaths were associated with 2009 influenza A (H1N1) virus infection, two were associated with an influenza A virus for which the subtype was undetermined, and one was associated with an influenza B virus infection.
* The proportion of outpatient visits for influenza-like illness (ILI) was 2.7% which is above the national baseline of 2.3%. Six of the 10 regions reported ILI at or above region-specific baseline levels. Regions 3, 6, 8 and 10 reported ILI below their region specific baselines.
* Fourteen states reported geographically widespread influenza activity, Puerto Rico and 25 states reported regional influenza activity, the District of Columbia and seven states reported local influenza activity, and the U.S. Virgin Islands, Guam and four states reported sporadic influenza activity.
During week 48, 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.
During week 48, 7.8% of all deaths reported through the 122-Cities Mortality Reporting System were due to P&I. This percentage was above the epidemic threshold of 7.1% for week 48. Including week 48, P&I mortality has been above threshold for 10 consecutive weeks.
Sixteen influenza-associated pediatric deaths were reported to CDC during week 48 (Alabama, Arizona [2], California [3], Colorado, Minnesota [4], Missouri [2], New Mexico, North Carolina, and Virginia). Thirteen of these deaths were associated with 2009 influenza A (H1N1) virus infection, two were associated with an influenza A virus for which the subtype is undetermined, and one was associated with an influenza B virus infection. The deaths reported during week 48 occurred between August 9 and December 5, 2009."
http://www.cdc.gov/flu/weekly/