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Before drug manufacturers ship vaccines to distributors they, along with the Food and Drug Administration (FDA), always test them to determine that they meet all safety and efficacy standards. As part of its quality assurance program, manufacturer Sanofi Pasteur, performs additional routine, ongoing tests of their flu vaccines to ensure that they continue to meet required specifications after they have been distributed health care providers.

This week, after performing these tests, Sanofi Pasteur notified Centers for Disease Control (CDC) and the FDA that the antigen content in a batch (known as a "lot") of syringes intended for children 6 months through 35 months of age distributed to providers in November, had dropped below a pre-specified limit making them slightly less potent.

Consequently, Sanofi Pasteur tested additional lots and found that three others also had an antigen content that had fallen below pre-specified limits. This means that doses from these four vaccine lots no longer meet the specifications for antigen content. Therefore, Sanofi is conducting a voluntary recall of these affected lots and has asked providers to return any vaccine they may have from these lots to the manufacturer.

The affected vaccine met all specifications at the time of release and both CDC and FDA have determined that there are no safety concerns for children who received this vaccine. Parents of children who received vaccines from the recalled lots do not need to take any action other than make sure their child receives their second dose if they have not already. There is NO need to revaccinate children who have received vaccine from these lots. The antigen content in the affected lots of vaccine is only slightly below the specification limit and experts expect it to still be effective against the H1N1 flu.

This drop in antigen content below the required specification only occurred in Sanofi Pasteur’s pediatric H1N1 monovalent vaccine in 0.25 mL pre-filled syringes. The same vaccine packaged in other forms, such as pre-filled syringes for older children and adults and multi-dose vials, continue to meet specifications.

For additional information please see CDC’s Questions and Answers related to the withdrawn vaccine at http://www.cdc.gov/h1n1flu/vaccination/syringes_qa.htm

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Written By:


Communications Office

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