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Finland Studying Genetics of Narcolepsy in Children Receiving GSK's Pandemic Flu Vaccine


Originally published Feb. 22.

The Finnish government will be investigating whether there are genetic causes for why 60 children and adolescents from 2009 and 2010 experienced narcolepsy after being vaccinated with GlaxoSmithKline's Pandemrix.

In an interim report released earlier this month, the National Narcolepsy Task Force wrote that due to a "joint effect of the vaccine and some other factors" Pandemrix vaccination "probably" contributed "to the observed increase in [the] incidence of narcolepsy among those four to 19-years of age."

The task force plans to release a final report on Aug. 31 after conducting further investigations into the epidemiologic, immunologic, and genetic causes for the onset of narcolepsy following vaccination with Pandemrix.

"The main aim of the immunologic studies is to clarify whether the immunological responses to the different components of the Pandemrix vaccine and to the [influenza] A (H1N1) virus among those children and teenagers with genetic disposition to narcolepsy and those fallen ill with narcolepsy differ from the immunological responses of other children and teenagers not belonging to these risk groups," Finland's National Institute for Health and Welfare said in a statement.

Around the same time the interim report from Finland was released, a World Health Organization expert panel stated that the incidence of narcolepsy seen with Pandemrix may indeed be due to genetic factors, since so far in Finland, genetic testing of 22 narcolepsy patients treated with the vaccine show that they all share a common gene linked to the illness. According to reports, approximately 30 percent of people in Finland have this gene associated with increased risk of narcolepsy, while 15 percent of Europeans have it.

According to the task force's interim findings, the vaccine-related narcolepsy does not appear to be attributable to a specific lot of faulty vaccines. To date, Pandemrix-related narcolepsy has been reported from 12 countries around the world, including Finland, Sweden and Iceland, where similar types of vaccines are used.

However, "contrary to the observations in Finland, narcolepsy has occurred in greater numbers than expected also among unvaccinated children and teenagers in Iceland," the NIHW said. "The association between narcolepsy and Pandemrix vaccine requires more investigations"

Following the release of the interim report from Finland's National Narcolepsy Task Force, the European Medicines Agency issued a statement expressing concern regarding the increasing number of narcolepsy cases in Finland, but felt that currently there is insufficient evidence that these adverse events are related to Pandemrix to warrant recommendations to curb the use of the vaccine.

According to the EMA's Committee for Medicinal Products for Human Use, or CHMP, the findings of the Finnish interim epidemiological study ─ comparing the incidence of narcolepsy in young people who were treated with Pandemrix to those not vaccinated with Pandemrix between Jan. 1, 2009, and Dec. 31, 2010 ─ may have been confounded by biases and other factors not considered in the investigation.

For the interim report, the National Narcolepsy Task Force gathered the data on the incidence of narcolepsy from hospital discharge registries during a two-year period. Researchers then linked this data with primary care records on pandemic vaccination.

"The observed association is so evident that it is unlikely that other so-called confounding factors could fully explain the phenomenon," stated the National Narcolepsy Task Force, which is a group of Finnish experts set up by the NIHW from various government institutes, hospitals and research organizations.

Of the 60 people the task force identified as getting narcolepsy, 52 people or 90 percent had received Pandemrix. "Based on the preliminary analyses, the risk of falling ill with narcolepsy among those vaccinated in the four to 19 years age group was nine-fold in comparison to those unvaccinated in the same age group," the task force reported. "This increase was most pronounced among those five to 15 years of age.

After the release of the interim report, GSK issued a statement maintaining that it would be "premature to draw any conclusions on a potential association between Pandemrix and narcolepsy" until the EMA's investigation, initiated in 2010, is complete.

According to the drug developer, more than 31 million doses of Pandemrix have been administered worldwide in 47 countries. "A total of 162 cases of narcolepsy in people vaccinated with Pandemrix have been reported to GSK as of Jan. 31, 2011; with 70 percent of these cases of narcolepsy originating from Finland and Sweden," GSK acknowledged.

The EMA and the Finish government both feel that the National Narcolepsy Task Force should investigate whether the association between Pandemrix and narcolepsy has been observed in places other than Finland. The EMA has pointed out, for instance, that there is widespread use of Pandemrix in Canada but a higher incidence of narcolepsy has not been seen in that region.

According to the NIHW, as of Jan. 24, Finland's National Vaccine Adverse Events Register had clocked 56 notifications of narcolepsy in association with Pandemrix vaccination. Of these, 54 incidences of narcolepsy occurred in the four-to-19 age bracket. NIHW has observed that symptoms of narcolepsy most commonly start two months after vaccination with Pandemrix is initiated.

Finland is participating in collaborative studies with nine European Union countries to evaluate whether pandemic vaccines and other risk factors are linked to an increased incidence of narcolepsy, and to track this adverse event in other countries. Results from these joint studies are slated for release in the early part of the summer.