CDC: Severe Flu Season Possible

This winter's flu season could be more severe than usual, the CDC is warning. While activity is low so far, most of the circulating virus is the H3N2 strain of influenza A, according to CDC Director Tom Frieden, MD. When H3N2 virus predominates, "we tend to have seasons that are worse flu years, with more hospitalizations from flu and more deaths from influenza," Frieden told reporters in a telephone briefing. In the week ending Nov. 22, he said, 91% of 1,200 samples tested were influenza A -- almost all of them H3N2 -- and 9% were influenza B. Only a small fraction were H1N1 influenza, which has predominated in recent years. But a second factor might foretell a bad flu season, Frieden said: Of the H3N2 samples, only 48% were matched to this year's vaccine and the majority of samples were "drifted" variants with slightly different immunogenic molecules. One possible implication, Frieden said, is that the seasonal vaccine now distributed across the country might be less effective than usual, although he added that sometimes vaccines remain effective against drifted strains. http://www.nytimes.com/2014/12/05/health/cdc-warns-that-flu-season-may-be-more-deadly-than-usual.html?_r=0