Swine Flu Vaccines Spoiled By The Heat, According To Manufacturers

ATLANTA (AP) — The makers of the nasal spray version of the flu vaccine say now they know why it has failed to protect young U.S. children against swine flu — fragile doses got too warm.

The AstraZeneca FluMist vaccine works well for most flu strains, but small studies found it didn’t work very well against the swine flu bug that first emerged in 2009. Swine flu has returned each year since but wasn’t a big player this flu season.

The problem first came to light last year, when swine flu was behind most illnesses. At a medical meeting Thursday, company officials said they investigated and concluded that the swine flu part of the vaccine is unusually sensitive to heat.

Flu vaccine is refrigerated, but it is allowed to be out at room temperature for up to two hours during distribution. The doses out on hot days were least effective, and company officials say it’s because they degraded and lost potency.

The company plans to use a more stable strain in the future.

FluMist is made using live but weakened virus, and is only approved for ages 2 to 49. Flu shots, made from killed virus, do not appear to be as vulnerable to heat, —> Read More Here


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