Reply #22: CDC comments re: flu vaccine cross-reactivity

[HereSince1628]

http://www.cdc.gov/ncidod/diseases/flu/weekly.htm


Antigenic Characterization: CDC has antigenically characterized 77 influenza A (H3N2) viruses submitted by U.S. laboratories since September 28. Of the 77 A (H3N2) viruses tested, 17 (22%) were similar antigenically to the vaccine strain A/Panama/2007/99 (H3N2), and 60 (78%) were similar to the drift variant, A/Fujian/411/2002 (H3N2), that predominated in Australia and New Zealand during the recent Southern Hemisphere influenza season. This drift variant is related to the vaccine strain, A/Panama/2007/99. Antibodies produced against the vaccine virus cross-react with A/Fujian/411/2002-like viruses, but at a lower level. Vaccine effectiveness depends, in part, on the match between vaccine strains and circulating viruses. Although vaccine effectiveness against A/Fujian/411/2002-like viruses may be less than that against A/Panama/2007/99-like viruses, it is expected that the current U.S. vaccine will offer some cross-protective immunity against the A/Fujian/411/2002-like viruses and reduce the severity of disease.