# 5803
Just over a year ago reports began to come out of Finland suggesting a link between an increase in the rate of narcolepsy among adolescents and GSK’s adjuvanted Pandemrix vaccine.
For early coverage of this story, you may wish to revisit Finland Suspends Use of Pandemrix Vaccine and EMA To Review Pandemrix Vaccine, both of which I wrote in August of 2010.
Despite some conflicting and incomplete data the European Medicines Agency issued a statement last July recommending:
In persons under 20 years of age Pandemrix to be used only in the absence of seasonal trivalent influenza vaccines, following link to very rare cases of narcolepsy in young people.
Note: The use of GSK’s 2009 monovalent Pandemrix vaccine has been largely supplanted by the introduction of last year’s trivalent vaccine, so the impact of this ruling should be minimal.
Stockpiles were released last winter in the UK during their surge in flu cases (see UK: To Release Pandemrix Vaccine Stockpile).
The EMA maintained, however, that despite these concerns over the Pandemrix vaccine, the overall benefit-risk remains positive.
Since then, we’ve seen a study that linked an increase in narcolepsy to the flu virus itself (see Stanford Study Finds Influenza – Narcolepsy Connection) - further confusing matters.
Today, Finland’s National Institute For Health and Welfare Narcolepsy Task Force has released a report where they find an association between the Pandemrix vaccine and increased rates of narcolepsy in children between the ages of 4 and 19.
Association between Pandemrix and narcolepsy confirmed among Finnish children and adolescents
1 Sep 2011
An association between Pandemrix and narcolepsy among children and adolescents in Finland is confirmed
In its final report, the National Narcolepsy Task Force confirms the tentative conclusion published in its Interim Report last January that the Pandemrix vaccine used in the winter of 2009–2010 contributed to the increased incidence of narcolepsy observed among 4–19-year-olds in Finland. According to the report, the increased risk associated with vaccination amounted to six cases of narcolepsy per 100 000 persons vaccinated in the 4–19 age group during the eight months following vaccination. This was 12.7 times the risk of a person in the same age group who had not been vaccinated. No increased incidence of narcolepsy was observed among children under the age of four or among adults over the age of 19.
In all the cases examined, narcolepsy associated with Pandemrix vaccination has been identified in persons who carry a genetic risk factor for narcolepsy. Because of this very strong association with the genetic risk factor which regulates immune responses, narcolepsy is considered an immune-mediated disease.
In approximately one quarter of those who developed narcolepsy following Pandemrix vaccination, the THL Immunology laboratory found antibodies binding to the AS03 adjuvant component of the vaccine. Adjuvants containing squalene have not previously been reported to induce the production of antibodies. The significance of this preliminary observation will be the subject of further research.
While more research is needed to nail down exactly what happened, and why, a few key points to ponder.
- Of the 3 dozen countries that used the Pandemrix vaccine in 2009-2010, only Finland and Sweden have documented an increase in Narcolepsy that they can link to the Pandemrix vaccine.
- At least a dozen countries reported increased rates of narcolepsy during that time period, including some countries where the vaccine was not used.
- In all the cases the task force examined, narcolepsy associated with Pandemrix vaccination was identified in persons who carry a genetic risk factor for narcolepsy
- Regarding the use of the vaccine, despite the the `unforeseen and deeply regrettable cases of narcolepsy’, Finland’s Narcolepsy taskforce found that its use probably saved lives and that `overall benefit-risk balance remains positive.’
- While unsure of its significance, researchers found antibodies binding to the AS03 adjuvant component of the vaccine in roughly 25% of the cases examined.
- And finally, adjuvanted flu vaccines like Pandemrix were not used in the United States.
Despite rare adverse side effects such as narcolepsy, flu vaccines have an excellent safety profile, and remain our best weapon against a virus that kills tens of thousands every year.
Taking any medicine – including a flu vaccine – entails a small degree of risk. But those risks pale when compared to the risks from catching the flu.
And with the potential for seeing an increase in antiviral resistant flu viruses that might limit your treatment options in the future (see Australia Reports Cluster Of Antiviral Resistant H1N1), doing what you can now to protect yourself against infection this winter makes a lot of sense.
