The European Medicines Agency, following its February monthly meeting, said that, while there remained "concern" about a possible link between the Pandemrix influenza vaccine and reports of narcolepsy among young people in Finland and Sweden, the data were "insufficient to establish a causal relationship."
Moreover, EMA said in a press release Feb. 18, other non-Nordic countries have not reported similar increased narcolepsy rates following vaccination with Pandemrix. The agency pointed to Canada as one country where Pandemrix use was widespread during the 2009 H1N1 pandemic, but increased narcolepsy reports did not follow.
The agency therefore elected not to change its recommendations on Pandemrix unless it receives more compelling data to suggest a link. The study submitted to EMA by the Finnish government had compared the incidence of narcolepsy in people aged 4-19 years who were vaccinated with Pandemrix between Jan. 1, 2009 and Dec. 31, 2010, with unvaccinated people the same age. The Finnish study also reported a ninefold increase in reports of narcolepsy in the vaccinated population (an increase from 1 to 9 cases per 100,000 vaccinated).
"One possible explanation for the results is that Pandemrix may have interacted with an unknown local environmental and/or genetic factor in contributing to an increased risk," EMA said. An ongoing study epidemiologic study of narcolepsy and pandemic vaccines is currently being conducted by the European Centre for Disease Control and Prevention in nine E.U. countries, with final results expected in June.