Risks of neurological and immune-related diseases, including narcolepsy, after vaccination with Pandemrix : a population- and registry-based cohort study with over 2 years of follow-up

• Objectives: To investigate the association between vaccination with Pandemrix and risk of selected neurological and immune-related diseases including narcolepsy.Design: Population-based prospective cohort study using data from regional vaccination registries and national health registries.Setting: Seven healthcare regions in Sweden comprising 61% of the Swedish population.Subjects: Study population of 3347467 vaccinated and 2497572 nonvaccinated individuals (vaccination coverage approximate to 60%) followed between 2009 and 2011 for 6.9 million person-years after exposure and 6.0 million person-years without exposure.Main outcome measure and analysis: First recorded diagnosis of neurological and immune-related diseases. Relative risks [hazard ratios (HRs) with 95% confidence intervals (CIs)] assessed using Cox regression, adjusted for covariates.Results: For all selected neurological and immune-related outcomes under study, other than allergic vaccine reactions (for which we verified an expected increase in risk) and narcolepsy, HRs were close to 1.0 and always below 1.3. We observed a three-fold increased risk of a diagnosis of narcolepsy (HR: 2.92, 95% CI: 1.78-4.79; that is, four additional cases per 100000 person-years) in individuals 20years of age at vaccination and a two-fold increase (HR: 2.18, 95% CI: 1.00-4.75) amongst young adults between 21 and 30years of age. The excess risk declined successively with increasing age at vaccination; no increase in risk was seen after 40years of age.Conclusions: For a large number of selected neurological and immune-related diseases, we could neither confirm any causal association with Pandemrix nor refute entirely a small excess risk. We confirmed an increased risk for a diagnosis of narcolepsy in individuals 20years of age and observed a trend towards an increased risk also amongst young adults between 21 and 30years.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Klinisk medicin -- Allmänmedicin (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Clinical Medicine -- General Practice (hsv//eng)

Nyckelord

cohort study

narcolepsy

neurological

immune-related diseases

Pandemrix

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)