By European Medicines Agency
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.
Tests on viral antibodies indicated that less than 10 per cent of the children and adolescents who developed narcolepsy had been infected with swine flu. Swine flu infection thus does not appear to play a significant role or be in joint effect with the Pandemrix vaccine in the onset of narcolepsy.
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