Bird flu: CDC checking to see if existing vaccines are well matched for current virus.

CDC probes if bird flu mutations impact vaccine stockpile The Centers for Disease Control and Prevention is investigating whether the U.S. stockpile of bird flu vaccines is still well matched to the virus after discovering recent mutations. Medical Xpress

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The CDC said Friday it identified genetic changes present in the virus, known commonly as H5N1, after sequencing samples from three people with the infection in California. The nation's top dairy state has identified six human cases this month, bringing the total number of U.S. infections this year to 20. Almost all have been workers in contact with sick animals.

The viruses, which appear closely related to those currently spreading in dairy cows, contained mutations that could have an impact on the nation's stockpile of bird flu vaccines. The CDC said it is examining whether its existing store of candidate vaccines are still well-matched to these viruses.

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