Pandemrix® vaccine and increased risk of narcolepsy

The National Institute of Health and Welfare of Finland issued a statement on 1 February 2011, indicating an increased risk of narcolepsy observed among children and adolescents vaccinated with Pandemrix®, an adjuvanted vaccine against pandemic influenza A(H1N1) 2009 manufactured by GlaxoSmithKline.

On the advice of the Finnish National Narcolepsy Task Force, the Institute concludes that vaccinated people aged 4–19 years had a risk of narcolepsy 9 times that of the unvaccinated. The Institute considers that the Pandemrix® vaccine was probably a contributing factor to this observed increase, but states that further investigation is needed of other significant co-factors associated with the increased risk of narcolepsy. The Task Force is expected to issue a final report by 31 August 2011.

Pandemrix® vaccine was used in 38 countries worldwide during the 2009/2010 season. Increased cases of narcolepsy have been observed only in Finland, Iceland and Sweden.

The issue of an increased narcolepsy rate has not been raised in association with the use of other pandemic influenza A(H1N1) 2009 vaccines, seasonal influenza vaccines or any other adjuvanted vaccines used in childhood immunization programmes.

WHO’s Global Advisory Committee on Vaccine Safety (GACVS) is considering all available data relating to reports of increased narcolepsy rates, and is expected to issue a statement on its web site in a few days.

WHO agrees that further investigation of this issue is required. In collaboration with a number of Member States of the European Union, the European Centre for Disease Prevention and Control (ECDC) is conducting a joint epidemiological study of narcolepsy and pandemic vaccines.

Recommendations for the use of influenza vaccines for the 2010/2011 season in children and adolescents remain unchanged.

WHO’s attention was first drawn to reports of narcolepsy following vaccination with Pandemrix® in Finland and Sweden in August 2010; it decided to monitor the situation through GACVS as new data became available. Updates will be provided as further information becomes available and is assessed.