Pandemrix safety profile updated due to narcolepsy reports
The European Medicines Agency (EMA), in its press release of 21 July 2011, recommended against the use of Pandemrix® in people aged under 20 years following reports of narcolepsy in recipients aged 4–19 years. This restriction applies to the use of the vaccine in the post-pandemic period and in settings where seasonal trivalent influenza vaccines formulated with influenza A(H1N1) 2009 antigen, in addition to other antigens, are available. The recommendation is based on the current risk–benefit analysis, and may change in future, when the benefit of vaccination with the product outweighs the risk of narcolepsy in young people.
Following recognition of risk signals in Finland and Sweden, indicating that vaccinated people had 6–13 times the risk of narcolepsy of the unvaccinated, several research initiatives were started at the national and European levels. The results of studies of background rates of narcolepsy in the general population before the pandemic and narcolepsy rates during the pandemic period were considered. In addition, studies on clinical presentation specifics of narcolepsy following immunization with the product and on other factors that are suspected to have contributed to disease onset will bring more understanding of the risk associated with the vaccine.
Individual narcolepsy cases were reported to several national regulatory authorities. No countries other than Finland, France and Sweden identified an excess of narcolepsy cases in the population aged 4–19 (1). These observations should be considered in view of vaccine utilization in the age group, differences in genetic and environmental factors, and delays in the making and validation of the narcolepsy diagnosis.
WHO’s Global Advisory Committee on Vaccine Safety is considering the available data, and is expected to issue a statement on its web site in a few days. WHO agrees that further investigation into narcolepsy onset following administration of Pandemrix® is required to understand its causes and the relationship between genetic, environmental and other factors.
In the upcoming influenza season, seasonal trivalent vaccines, formulated according to WHO recommendation, will be used. These vaccines, irrespective of their manufacturer, have not been associated with narcolepsy. They are considered safe and effective in all age groups. An increased risk of narcolepsy has not been found in association with any other vaccines, including those used in infant and childhood immunization programmes.
(1) The risk signal was excess cases of narcolepsy in the group aged 4–19 years in Finland and Sweden, and in the group aged 10–15 in France.