Sanofi-Aventis is recalling about 800,000 doses of the H1N1 vaccine after it was discovered that some batches had lost potency after time, the Wall Street Journal is reporting.

During quality assurance testing, it was revealed that four batches of the vaccine marketed for babies and young children had lost potency. Providers have been asked to return unused doses from the lots named in the recall. A CDC spokesman said that the affected vaccines represent less than 1% of more than 95 million doses currently available in the US and did not present any safety risk to the target patients in the 6-36 month age group. The CDC also says that children vaccinated from the affected lots do not need to be revaccinated.

It is recommended that children receive two doses of the vaccine a month apart. Parents are advised that children who were vaccinated from the affected lots still receive the second dose of H1N1 vaccine if they haven’t already.

[WSJ]