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FRIMEDBIO-Fri prosj.st. med.,helse,biol

The Norwegian Influenza Registry Study, RegFlu II: Pandemic influenza, vaccination and neurological disease

Awarded: NOK 6.8 mill.

In this project we use Norwegian registries to study consequences of influenza infection and influenza vaccination. The project was inititated after the influenza pandemic in 2009. After the pandemic, reports of narcolepsy after vaccination with Pandemrix appeared in the Nordic region, with an increase of narcolepsy cases, mainly among children and young adults. The public concern regarding the safety of vaccination in general and vaccines with new adjuvants in particular was substantial. There are several methodological challenges related to studying the association between influenza, vaccination and narcolepsy. We have linked several national registries, and include Influenza diagnoses from primary health care. Information on other underlying risk conditions are also investigated, and will be included in multivariable statistical analysis, which will help us disentangle effects of influenza infection versus vaccination effects. The narcolepsy diagnoses will be verified and classified according to diagnositic criteria through information from hospital records. Looking at time trends, spatial occurrence and clustering in certain population subgroups we may also increase our understanding of the complex mechanisms involved. We are also investigating any associations with other neurological outcomes and autoimmune conditions. We and are now in the process of analyzing data and publishing results.

During the H1N1 influenza pandemic in 2009, vaccination with an adjuvanted influenza vaccine was widely used. After the pandemic, reports of narcolepsy after vaccination with Pandemrix have appeared in the Nordic region, with an increase of narcolepsy cas es, mainly among children and young adults. The public concern regarding the safety of vaccination in general and vaccines with new adjuvants in particular is substantial. There are several methodological challenges related to studying the association bet ween influenza, vaccination and narcolepsy. Public awareness after the early alarm in August 2010 could lead to earlier referral and shorter time from symptoms to diagnosis for vaccinated children, biasing relative risks upwards. Also, it could be easier to recruit vaccinated narcolepsy patients than unvaccinated patients in case control studies, giving too strong associations between vaccination and narcolepsy. Another problem is to disentangle consequences of vaccination from those of influenza infectio n. There could also be completely unrelated exposures explaining the increases in the incidence of narcolepsy in these countries. Unless these problems are resolved, it will be difficult to make sound decisions on the use of this type of vaccines in the future, particularly for children and adolescents. We can contribute to resolve these problems in our research approach. We will link several national registries, and look at exposure-effect periods before and after the public awareness, and by restricti ng to the most severe conditions diagnosed relatively quickly. Influenza diagnoses from primary health care will be included in multivariable statistical analysis, which will help us disentangle effects of influenza infection versus vaccination effects. L ooking at time trends, spatial occurrence and clustering in certain population subgroups we may also investigate if there are other exposures that can explain the sudden increase in narcolepsy.

Funding scheme:

FRIMEDBIO-Fri prosj.st. med.,helse,biol

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