Table 1. Characteristics of patients hospitalised due to laboratory-confirmed influenza, Catalonia, influenza seasons 2010/11–2015/16 (n = 1,711).

Characteristics	Total		Vaccinated		Unvaccinated		p value
	n	%	n	%	n	%
All cases	1,711	100	450	100	1,261	100	NA
Sex
Male	975	57	264	58.7	711	56.4	0.401
Female	736	43	186	41.3	550	43.6
Age
18–64	799	46.7	71	15.8	728	57.7	< 0.001
≥ 65	912	53.3	379	84.2	533	42.3
Type of influenza virus
A	1,470	85.9	375	83.3	1,095	86.8	0.067
B	241	14.1	75	16.7	166	13.2
Comorbidities
Obesity (BMI > 40)	181	10.6	50	11.1	131	10.4	0.669
COPD	441	25.8	159	35.3	282	22.4	< 0.001
Diabetes mellitus	425	24.8	156	34.6	269	21.3	< 0.001
Chronic renal disease	235	13.7	94	28.9	141	11.2	< 0.001
Immunodeficiency	333	19.5	74	16.4	259	20.5	0.060
Chronic cardiovascular disease	504	29.5	202	44.9	302	23.9	< 0.001
Chronic liver disease	112	6.5	21	4.7	91	7.2	0.063
Complications
Pneumonia	1,277	74.9	316	70.2	961	76.2	0.016
ARD	1,019	60.8	144	32.0	513	40.7	0.001
Multi-organ failure	176	10.6	40	8.9	136	10.8	0.270
ICU admission	591	34.5	108	24.0	483	38.3	< 0.001
Death	223	13.0	63	14.0	160	12.7	1.533
Pregnancya	26	1.5	0	0.0	26	2.1	NC

ARD: Acute respiratory distress; BMI: body mass index; COPD: chronic obstructive pulmonary disease; ICU: intensive care unit; NA: not applicable; NC: not calculable.

^aPregnancy was not considered a complication and was in another category.