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PLoS One. 2014 Sep 29;9(9):e108489. doi: 10.1371/journal.pone.0108489. eCollection 2014.

Risk of narcolepsy associated with inactivated adjuvanted (AS03) A/H1N1 (2009) pandemic influenza vaccine in Quebec.

Author information

1
Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur, and Department of Psychiatry, University of Montreal, Montreal, Canada.
2
Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur, Montreal, Canada.
3
Quebec National Public Health Institute (Institut national de santé publique du Québec), Quebec City, Canada.
4
Quebec University Hospital Research Centre, Quebec City, Canada.
5
Centre for Advanced Research in Sleep Medicine, Hôpital du Sacré-Coeur, and Department of Medicine, University of Montreal, Montreal, Canada.
6
Stanford Center for Sleep Sciences and Medicine, Stanford University of Medicine, Palo Alto, CA, United States of America.
7
Department of Social and Preventive Medicine, Laval University, Quebec City, Canada.

Abstract

CONTEXT:

An association between an adjuvanted (AS03) A/H1N1 pandemic vaccine and narcolepsy has been reported in Europe.

OBJECTIVE:

To assess narcolepsy risk following administration of a similar vaccine in Quebec.

DESIGN:

Retrospective population-based study.

SETTING:

Neurologists and lung specialists in the province were invited to report narcolepsy cases to a single reference centre.

POPULATION:

Patients were interviewed by two sleep experts and standard diagnostic tests were performed. Immunization status was verified in the provincial pandemic influenza vaccination registry.

MAIN OUTCOME MEASURES:

Confirmed narcolepsy with or without cataplexy with onset of excessive daytime sleepiness between January 1st, 2009, and December 31st, 2010. Relative risks (RRs) were calculated using a Poisson model in a cohort analysis, by a self-controlled case series (SCCS) and a case-control method.

RESULTS:

A total of 24 cases were included and overall incidence rate was 1.5 per million person-years. A cluster of 7 cases was observed among vaccinated persons in the winter 2009-2010. In the primary cohort analysis, 16-week post-vaccination RR was 4.32 (95% CI: 1.50-11.12). RR was 2.07 (0.70-6.17) in the SCCS, and 1.48 (0.37-7.03) using the case-control method. Estimates were lower when observation was restricted to the period of pandemic influenza circulation, and tended to be higher in persons <20 years old and for cataplexy cases.

CONCLUSIONS:

Results are compatible with an excess risk of approximately one case per million vaccine doses, mainly in persons less than 20 years of age. However, a confounding effect of the influenza infection cannot be ruled out.

PMID:
25264897
PMCID:
PMC4180737
DOI:
10.1371/journal.pone.0108489
[Indexed for MEDLINE]
Free PMC Article

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