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UPDATED: Study links GSK's swine flu vaccine to narcolepsy in adults

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Evidence linking GlaxoSmithKline's ($GSK) swine flu vaccine Pandemrix to heightened risk of narcolepsy has emerged piecemeal over the past few years. It began in 2011 with data linking the vaccine to narcolepsy in kids and has since expanded to suggest adults are at risk too.

The link between Pandemrix and narcolepsy in adults was first made by French researchers. A Swedish paper added to the evidence 6 months later, but both projects had limitations. Now a more comprehensive research project from Finland has identified the link as well. The Finnish research looked at validated pre- and post-vaccination health records for evidence of narcolepsy. A three- to fivefold increase in the risk of developing the disorder was found in vaccinated adults 20 to 64 years old.

From 2009 to 2011, 25 adults developed narcolepsy in Finland, 18 of whom had received GSK's swine flu shot. Almost all of the cases were in people under the age of 40, and none were seen in anyone over the age of 64. The finding suggests that the risk of developing narcolepsy tails off with age. Finnish researchers put the increased risk of narcolepsy in adults at 1/100,000. In children it is 6/100,000. The Finnish National Institute for Health and Welfare thinks these figures may overestimate the risks, though. If vaccinated people sought treatment for narcolepsy sooner, the risk may be lower than currently thought.

Finnish researchers are looking into this as a follow-up study but doubt anything will change the primary conclusion that the Pandemrix vaccination is linked to increased risk of narcolepsy in adults. But the finding must be put in context. Register surveillance suggests Pandemrix saved 50 lives in Finland in the first year after vaccination and prevented 80,000 swine flu infections. In the most recent flu season, H1N1 was still present in Finland and killed 14 people. Even several years after the vaccinations, Pandemrix is believed to provide more than 50% protection against swine flu.

In a separate development, GSK has bought Swiss vaccine developer Okairos for $325 million. Okairos--a 2012 Fierce 15 company--spun out of Merck ($MRK) 6 years ago. Since then it has worked on T-cell-based infectious disease vaccines, advancing a malaria shot into Phase II. In March, GSK reported weak results for its own malaria vaccine.

- here's the Finnish release
- read the AFP's take
- see FierceBiotech's Okairos article

Related Articles:
Swedish study adds to data linking GSK vax to narcolepsy
FDA moves decision day for GSK pandemic vaccine, but why?
CDC preps for emerging swine flu strain

Editor's note: The story has been updated with information about GSK's takeover of Okairos.