Sanofi Pasteur has recalled six additional prefilled syringe lots of its influenza A (H1N1) 2009 monovalent vaccine after routine testing found that the antigen content had declined below the specification limit.

Sanofi Pasteur recalled a similar four lots of paediatric H1N1 vaccine in December 2009 after routine stability testing showed that those lots no longer met the potency specification.

The US Food and Drug Administration (FDA) and the US Centres for Disease Control and Prevention (CDC) have evaluated the data and agree that there are no safety issues and that individuals immunised with these lots do not need re-immunisation.

No action is needed other than to return unused doses from the recalled lots. Sanofi Pasteur is working closely with the FDA and the CDC to notify those who have administered the vaccine.