Table 3. 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.

Observation period	Post-vaccinationrisk period	Post-vaccinationbuffer period	Brighton level	No of casesin analysis	Relative risk	95% confidenceinterval	Attributable risk per million doses (95% confidence intervals)
All ages
6 months (183 days) beforevaccination to 6 monthsafter vaccination	16 weeks (112 days)	Weeks 17–24(days 113–168)	1–3	13	2.07	0.70 to 6.17	0.82 [−068 to 1.32]
			1–2	9	3.55	0.89 to 14.21	0.97 [−0.17 to 1.26]
		No buffer	1–3	13	2.66	0.89 to 7.90	0.99 [−0.19 to 1.38]
			1–2	9	4.55	1.14 to 18.21	1.06 [0.17 to 1.28]
Persons 6 months to <20 years of age
6 months (183 days) beforevaccination to 6 monthsafter vaccination	16 weeks (112 days)	Weeks 17–24(days 113–168)	1–3	8	2.96	0.71 to 12.39	2.98 [−1.84 to 4.14]
			1–2	5	7.10	0.79 to 63.59	3.09 [−0.96 to 3.54]
		No buffer	1–3	8	3.79	0.90 to 15.89	3.31 [−0.50 to 4.22]
			1–2	5	9.11	1.02 to 81.48	3.21 [0.07 to 3.56]
Persons ≥20 years of age
6 months (183 days) beforevaccination to 6 monthsafter vaccination	16 weeks (112 days)	Weeks 17–24(days 113–168)	1–3	5	1.18	1.19 to 7.09	0.09 [−2.58 to 0.52]
			1–2	4	1.78	0.25 to 12.61	0.26 [−1.81 to 0.56]
		No buffer	1–3	5	1.52	0.25 to 9.08	0.21 [−1.81 to 0.54]
			1–2	4	2.27	0.32 to 16.16	0.34 [−1.28 to 0.57]