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VACCINE SAFETY: UPDATE ON PANDEMIC INFLUENZA VACCINE (PANDEMRIX®) AND NARCOLEPSY

Sunday, 21st of July 2013

• UPDATE ON PANDEMIC INFLUENZA VACCINE (PANDEMRIX®) AND NARCOLEPSY

The committee has previously reviewed data from studies on the use of the pandemic influenza vaccine (monovalentA(H1N1)pdm09 vaccine) in Finland, Sweden,Ireland, the UK and France which all demonstrated an increased risk of narcolepsy following Pandemrix® vaccination in children and adolescents. The studies in Sweden and France also found evidence of an increased risk in adults. The Committee reviewed newly available data from Finland about the safety of Pandemrix® vaccine in adults. The retrospective cohort study linked vaccination data of the whole adult population to incident cases of narcolepsy identified through the national care register during the follow-up period from 1 January 2009 to 31 December 2011. The comparison of incidence rates indicated a 3–5-fold (after sensitivity analysis 2–4-fold) risk of narcolepsy among vaccinated compared to unvaccinated adults. The increased risk was seen 8 months post vaccination; thereafter, no increased risk was observed. The reports from Sweden,

France and Finland concur that young adults have an increased risk of narcolepsy after Pandemrix® vaccination. GACVS acknowledges this finding suggesting a possible risk of narcolepsy among adults, although it remains lower than that seen among children. Further follow-up research is required to confirm the strength of the observed association and size of the risk. Because of the continued threat of emergence of new pandemics and the expected need for new pandemic vaccines, the Committee reiterated the urgency of continued research to identify the underlying biological mechanisms of this association.