H1N1 Swine Flu Vaccine Recall: CDC Expropriates 800,000 Doses
The Center For Disease Control And Prevention (CDC) warned that 800,000 doses of H1N1 swine flu vaccine distributed throughout the United States will be recalled. The recall was caused by a drop in the potency of the vaccine, which might result in reduced vaccine effectiveness. The recalled vaccine was intended for small children aged six months old to three years old. The lot was manufactured by Sanofi Pasteur and consisted of pre-filled syringes containing 0.25 mL of the H1N1 vaccine. Children who have already been vaccinated from the batch do not need to be re-vaccinated as the vaccine likely lost potency after the shots were administered. Moreover, the antigen content is now “only slightly below” the specified range and is still expected to be effective in stimulating a protective response. CDC emphasized the parents of these children "do not need to take any action."
The potency of the vaccine can be affected by storage conditions, like light exposure, alkalinity and temperature cycles. The H1N1 swine flu vaccine is protein based and needs very strict transportation conditions to keep vaccine potent. Changes in storage conditions can affect configurations of the delicate proteins contained in the vaccine, potentially disabling some of the virus specific epitopes. Reduced vaccine potency may lead to an insufficient immune response to the H1N1 virus.
CDC maintains the recall is "non-safety-related" and "voluntary." It also says vaccine batches are routinely tested for purity, potency and safety prior to release.