Risk of narcolepsy ± narcolepsy associated with A/H1N1 (2009) vaccination using the cohort method according to observation period and post-vaccination risk period, in Quebec, 2009–2010.

<p><i>+: Cases with onset after vaccination during risk period; E−: Cases not vaccinated or with onset before vaccination or after end of risk period.</i></p><p><i>*Primary analysis defined a priori.</i></p><p>Risk of narcolepsy ± narcolepsy associated with A/H1N1 (2009) vaccination using the cohort method according to observation period and post-vaccination risk period, in Quebec, 2009–2010.</p

Risk of Narcolepsy Associated with Inactivated Adjuvanted (AS03) A/H1N1 (2009) Pandemic Influenza Vaccine in Quebec

<div><p>Context</p><p>An association between an adjuvanted (AS03) A/H1N1 pandemic vaccine and narcolepsy has been reported in Europe.</p><p>Objective</p><p>To assess narcolepsy risk following administration of a similar vaccine in Quebec.</p><p>Design</p><p>Retrospective population-based study.</p><p>Setting</p><p>Neurologists and lung specialists in the province were invited to report narcolepsy cases to a single reference centre.</p><p>Population</p><p>Patients were interviewed by two sleep experts and standard diagnostic tests were performed. Immunization status was verified in the provincial pandemic influenza vaccination registry.</p><p>Main Outcome Measures</p><p>Confirmed narcolepsy with or without cataplexy with onset of excessive daytime sleepiness between January 1^st, 2009, and December 31^st, 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.</p><p>Results</p><p>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.</p><p>Conclusions</p><p>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.</p></div

Risk of narcolepsy ± narcolepsy associated with A/H1N1 (2009) vaccination using the ‘self-controlled case-series method’ according to age and diagnostic classification, in the province of Quebec, 2009–2010.

<p>Risk of narcolepsy ± narcolepsy associated with A/H1N1 (2009) vaccination using the ‘self-controlled case-series method’ according to age and diagnostic classification, in the province of Quebec, 2009–2010.</p

Distribution of 24 narcolepsy cases according to exposure status and patients’ characteristics.

<p>*Fisher exact test for proportions and Wilcoxon rank test for medians.</p><p>Distribution of 24 narcolepsy cases according to exposure status and patients’ characteristics.</p

Weekly incidence, weekly prevalence and cumulative incidence of schools reporting an absenteeism rate ≥10%.

<p>Weekly incidence, weekly prevalence and cumulative incidence of schools reporting an absenteeism rate ≥10%.</p

Proportion of elementary and high schools that continued to report an absenteeism rate ≥10% since the day of first reporting by school size.

<p>Proportion of elementary and high schools that continued to report an absenteeism rate ≥10% since the day of first reporting by school size.</p

Distribution of the maximal absenteeism rate by school size (all schools) and regression line.

<p>Distribution of the maximal absenteeism rate by school size (all schools) and regression line.</p

Distribution of the number of days of reporting by school size (all schools) and regression line.

<p>Distribution of the number of days of reporting by school size (all schools) and regression line.</p

Weekly incidence of affected schools from week 43 to week 48(six upper panels); cumulative incidence of affected schools in the province at the end of the study (bottom left panel); cumulative incidence of affected schools in the regions of Montreal and Laval at the end of the study (bottom right panel).

<p>Weekly incidence of affected schools from week 43 to week 48(six upper panels); cumulative incidence of affected schools in the province at the end of the study (bottom left panel); cumulative incidence of affected schools in the regions of Montreal and Laval at the end of the study (bottom right panel).</p

Distribution of the maximum absenteeism rate reported by schools and interval between first reporting of ≥10% absenteeism and the maximum rate in the school.

<p>Distribution of the maximum absenteeism rate reported by schools and interval between first reporting of ≥10% absenteeism and the maximum rate in the school.</p