Investigation of an association between onset of narcolepsy and vaccination with pandemic influenza vaccine, Ireland April 2009-December 2010.

Abstract

In 2011, the Irish Medicines Board received reports of onset of narcolepsy following vaccination against influenza A(H1N1)pdm09 with Pandemrix. A national steering committee was convened to examine the association between narcolepsy and pandemic vaccination. We conducted a retrospective population-based cohort study. Narcolepsy cases with onset from 1 April 2009 to 31 December 2010 were identified through active case finding. Narcolepsy history was gathered from medical records. Pandemic vaccination status was obtained from vaccination databases. Two independent experts classified cases using the Brighton case definition. Date of onset was defined as date of first healthcare contact for narcolepsy symptoms. Incidence of narcolepsy in vaccinated and non-vaccinated individuals was compared. Of 32 narcolepsy cases identified, 28 occurred in children/adolescents and for 24 first healthcare contact was between April 2009 and December 2010. Narcolepsy incidence was 5.7 (95% confidence interval (CI): 3.4–8.9) per 100,000 children/adolescents vaccinated with Pandemrix and 0.4 (95% CI: 0.1–1.0) per 100,000 unvaccinated children/adolescents (relative risk: 13.9; absolute attributable risk: 5.3 cases per 100,000 vaccinated children/adolescents). This study confirms the crude association between Pandemrix vaccination and narcolepsy as observed in Finland and Sweden. The vaccine is no longer in use in Ireland. Further studies are needed to explore the immunogenetic mechanism of narcolepsy.

• Authors: D O'Flanagan, A S Barret, M Foley, S Cotter, C Bonner, C Crowe, B Lynch, B Sweeney, H Johnson, B McCoy, E Purcell
• Journal: Euro surveillance : bulletin Europeen sur les maladies transmissibles = European communicable disease bulletin (Euro Surveill) Vol. 19 Issue 17 Pg. 15-25 (May 01 2014) ISSN: 1560-7917 [Electronic] Sweden
• PMID: 24821121 (Publication Type: Comparative Study, Journal Article)

Chemical References

• Influenza Vaccines
• pandemrix

Topics

• Adolescent
• Child
• Child, Preschool
• Female
• Humans
• Incidence
• Infant
• Infant, Newborn
• Influenza A Virus, H1N1 Subtype
• Influenza Vaccines (administration & dosage, adverse effects)
• Ireland (epidemiology)
• Male
• Narcolepsy (epidemiology, etiology)
• Odds Ratio
• Pandemics (prevention & control)
• Population Surveillance
• Retrospective Studies
• Risk
• Vaccination (statistics & numerical data)
• Young Adult