MMWR: US Influenza Activity 2009-10 Season

 

 

 

# 4768

 

The ongoing post-mortem on this past year’s influenza season continues with today’s release in the CDC’s MMWR of a summary of influenza activity in the United States.

 

I’ll just post the opening paragraph, and a few selected bullet points from the text. They indicate, as many experts have previously stated, that this past pandemic flu season wasn’t quite as benign as some might have you believe.

 

Follow the link to read it the report in its entirety.

 

Update: Influenza Activity --- United States, 2009--10 Season

Weekly

July 30, 2010 / 59(29);901-908

During the 2009--10 influenza season, the second wave of influenza activity from 2009 pandemic influenza A (H1N1) occurred in the United States; few seasonal influenza viruses were detected. Influenza activity* peaked in late-October and was associated with higher pediatric mortality and higher rates of hospitalizations in children and young adults than in previous seasons.

 

The proportion of visits to health-care providers for influenza-like illness (ILI), as reported in the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet), was among the highest since ILI surveillance began in 1997 in its current form. This report summarizes influenza activity in the United States during the 2009--10 influenza season (August 30, 2009--June 12, 2010).

(Continue . . .)

 

A few selected highlights include . . .

  • 740,000 influenza specimens were tested for influenza, and the number of laboratory-confirmed positives was approximately four times the average of the previous four seasons

  • three cases, identified in Kansas, Iowa, and Minnesota, were isolated cases of human infections with contemporary North American swine-lineage influenza A (H3N2) viruses currently circulating in swine herds

  • ILI activity next exceeded baseline beginning the week ending August 23, 2009, and continued to be elevated above baseline through January 2, 2010, for a total of 19 consecutive weeks

  • August 30, 2009, through June 12, 2010, the peak proportion of outpatient visits to healthcare providers for ILI was among the highest seen since the system began in its current form in 1997 and was approximately equal to that seen during the 2003--04 influenza season

  • During the 2009--10 influenza season, the percentage of deaths attributed to pneumonia and influenza (P&I) exceeded the epidemic threshold†† for 13 consecutive weeks, from October 3 to December 26, 2009, and from January 16 to January 30, 2010 (Figure 4). 

  • From August 30, 2009, to June 12, 2010, the 2009--10 influenza season, a total of 279 laboratory-confirmed, influenza-associated pediatric deaths were reported, nearly four times the average reported in the previous five influenza seasons

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