US flu season still going strong

Lisa Schnirring  Staff Writer

Mar 4, 2011 (CIDRAP News) – The nation's flu activity remained high last week, with the number of pediatric deaths more than doubling from the previous week and most states still reporting widespread cases, the US Centers for Disease Control and Prevention (CDC) said today.

Children are among the groups that flu is hitting the hardest. The CDC received reports of 14 pediatric flu deaths, 8 more than the previous week, raising the season's total to 55. Hospitalization rates in children younger than 4 are higher than those for all other age-groups except those older than 65.

Four of the pediatric flu deaths were linked to influenza B, four to 2009 H1N1, two to H3N2, and four to unsubtyped viruses.

However, the percentage of deaths attributed to flu and pneumonia overall continued a slow decline, falling from 8.3% to 8.0% last week, putting it at the epidemic threshold, the CDC said. The agency added that this flu indicator has been at or above baseline for 5 consecutive weeks.

The proportion of doctor's visits for flulike illness dropped from 4.9% to 4.0% last week, which is still well above the national baseline of 2.5%. The share of respiratory specimens testing positive for flu fell slightly from 31.3% the previous week to 27.9% last week.

Forty-four states reported widespread flu activity, the same as the week before. Regional activity was reported by Alabama, Florida, Hawaii, Mississippi, and Utah. Oregon and Washington, DC, reported local activity.

All flu subtypes continued to circulate widely. Influenza A accounted for 74% of positive samples and influenza B for 26%. Among influenza A isolates, 32.4% were H3N2, 23.1% were 2009 H1N1, and 44.5% were unsubtyped. The CDC noted the predominant virus has varied by week, by region, and even between states in the same region.

See also:

Mar 4 CDC flu surveillance update