Table 3. Effect of influenza vaccination in reducing severe outcomes in patients hospitalised due to laboratory-confirmed influenza, Catalonia, Spain, influenza seasons 2010/11–2015/16 (n = 1,727).

Characteristics	ICU/death (n = 692)		Non-ICU/death (n = 1,035)		Adjusted OR	95% CI	p value
	n	%	n	%
Seasonal vaccine
Yes	146	21.3	304	29.7	0.78	(0.61 to 0.99)	0.048
No	540	78.7	721	70.3	Ref
Age
18-64 years	386	55.8	422	40.8	Ref
≥ 65 years	306	44.2	613	59.2	0.56	(0.45 to 0.68)	< 0.001
Comorbidities
Yes	520	75.1	765	73.9	1.36	(1.07 to 1.73)	0.011
No	172	24.9	270	26.1	Ref

CI: confidence interval; ICU: intensive care unit; OR: odds ratio; Ref: reference.