February 1, 2011
Study Suggests H1N1 Vaccine Raises Narcolepsy Risk
The World Health Organization (WHO) is reviewing the safety of GlaxoSmithKline's Pandemrix H1N1 flu vaccine after a Finnish study suggested children who got the shot were nine times more likely to suffer from narcolepsy.
The rare sleeping disorder causes a person to fall asleep suddenly and unexpectedly
Its cause is not understood but it is generally consider to be triggered by a combination of genetic and environmental factors.
Researchers at Finland's National Institute for Health and Welfare (NIHW) said Tuesday that their findings suggest it was "most likely" that the increase they in narcolepsy was a joint effect of Pandemrix and some other factor or factors.
Their research, which was conducted by the Finnish national narcolepsy committee and published by the NIHW, found an increase in cases of narcolepsy among children between the ages four and 19 years who had the vaccine.
GSK said it was aware of the research but believed it was too soon to draw any conclusions. An investigation by European drugs regulators is already underway.
The Geneva-based WHO said in a statement that further investigation was required "concerning narcolepsy and Pandemrix vaccine" and it was working on this.
"WHO's Global Advisory Committee on Vaccine Safety (GACVS) is considering all available data relating to reports of increased rates of narcolepsy and is expected to issue a statement on its website within the coming days," it said.
It said that recommendations for the use of seasonal flu vaccines for 2010/2011 remain unchanged. The issue of narcolepsy had not been linked with any other H1N1 pandemic flu vaccines, seasonal flu vaccines or any other adjuvanted vaccines used in childhood immunizations programs.
GSK said it was reviewing the report and "it would be premature to draw any conclusions on a potential association between Pandemrix and narcolepsy until this European investigation has been completed."
Hanna Nohynek, the NIHW's vaccine safety officer, told Reuters the baseline risk of narcolepsy in children aged four to 19 was less than 1 per 100,000, and the study found that among those who had the Pandemrix shot the risk jumped to 8.1 per 100,000.
GSK said that over 31 million doses of Pandemrix have been administered around the world in 57 countries. The company said that it had received reports of a total of 162 cases of narcolepsy as of January 31, 2011, with 70 percent of these cases originating from Finland and Sweden.
The Finnish researchers' report said that during 2009 and 2010, 60 children and adolescents between the ages four and 19 fell ill in Finland with Narcolepsy.
It said that 90 percent of those who fell ill had received Pandemrix, and the vaccine coverage in the entire age group was 70 percent.
The Finnish institute said it would seek to confirm its findings in further investigations by August 2011.
On the Net:
- WHO Global Advisory Committee on Vaccine Safety (GACVS)
- National Institute for Health and Welfare (NIHW) Statement