HHS: Most H5N1 vaccine on hand is still potent

Nov 17, 2006 (CIDRAP News) – A Department of Health and Human Services official said today that loss of potency is affecting less than 20% of H5N1 avian influenza vaccine doses in the national stockpile, not a majority of doses as reported here yesterday.

Bill Hall, an HHS spokesman in Washington, DC, said the agency has acquired a total of about 7.5 million doses of H5N1 vaccine to date, and about 200,000 of those have been used for research.

About 1.4 million doses have begun to lose potency, Hall said. "That leaves about 5.9 million doses that are mostly in bulk, with some in vials, that still have potency," he said. "That would treat about 3 million people."

Hall gave the numbers in response to the report here yesterday in which he was quoted as saying that a majority of vaccine doses in the stockpile had begun to lose potency. He said his comments were mischaracterized.

HHS has been stockpiling H5N1 vaccine in preparation for the threat of an influenza pandemic sparked by the avian flu virus. In a Nov 13 pandemic planning update, HHS Secretary Mike Leavitt said the agency had enough vaccine on hand for about 3 million people. A previous update in July said the stockpile contained enough vaccine for about 4 million people.

Hall cited the loss of potency in some of the vaccine as the main reason for the decrease in the number of people who could be immunized.

Most of the vaccine was made by Sanofi Pasteur, but HHS also has bought some from Chiron Corp., Hall said today.

He reiterated today that all vaccines and other biologic products have a limited shelf life. "The expected shelf life of seasonal flu vaccine is probably about a year," so the fact that most of the stockpile is still good after about 2 years "is probably a good thing," he said.

Hall added that HHS-sponsored research now under way, particularly on the use of adjuvants (immune-boosting substances), may help to stretch the vaccine supply.

See also:

Nov 13 HHS pandemic planning update
http://www.flu.gov/professional/pdf/panflureport3.pdf

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