Will new pandemic influenza A (H1N1) vaccines be safe? Licensed vaccines, including influenza vaccines, are held to a very high standard of safety. Likewise, all possible precautions will be taken to ensure safety of new pandemic vaccines and results from clinical trials, currently ongoing or soon to be initiated, will be taken into consideration by the regulatory authorities in their decision to license pandemic vaccines.
In early June, WHO held a consultation of experts which reviewed the safety of adjuvants, or substances added to vaccines to make them more effective; no significant safety concerns were identified. Vaccine safety will be carefully monitored through post-marketing surveillance. How can a repeat of the 1976 swine flu vaccine complications (Guillain-Barré syndrome) experienced in the United States of America be avoided? Guillain-Barré Syndrome (GBS) is an acute disorder of the nervous system. It sometimes develops following a variety of infections, including influenza. Studies suggest that seasonal influenza vaccines could sometimes be associated with an increased risk of Guillain-Barré syndrome on the order of one to two cases per million vaccinated persons. During the 1976 influenza vaccination campaign, about 10 persons per million vaccinated persons developed GBS which stopped the vaccination campaign and led to the withdrawal of the vaccine. The reason why GBS developed in association with that specific vaccine has never been firmly established. The potential for the development of a similar risk with future vaccines can never be firmly excluded.
However, the influenza A (H1N1) vaccine will be manufactured according to established standards and post marketing surveillance will be conducted to monitor potential development of any serious adverse events following administration of vaccine. Safety monitoring systems are an integral part of strategies for the implementation of the new pandemic influenza vaccines. Who will approve (license) new influenza A (H1N1) vaccines for use? Regulatory approval for new influenza A (H1N1) vaccines will be conducted by national authorities. National regulatory authorities have put into place expedited processes that do not compromise on the quality and safety of the vaccine.