Table 1. Distribution of cases and controls according to demographic variables, medical conditions and vaccination history.

Characteristics	Cases (N = 1895)	Controls (N = 1895)	Crude OR (95% CI)	p-value
Age group
65–74 years	592 (31.2%)	603 (31.8%)	1
75–84 years	879 (46.4%)	897 (47.3%)	1.17 (0.84–1.64)	0.36
≥85 years	424 (22.4%)	395 (20.8%)	1.69 (1.07–2.68)	0.03
Sex
Female	746 (39.4%)	746 (39.4%)	-
Male	1149 (60.6%)	1149 (60.6%)	-
Marital status
Married/Cohabiting	1099 (58.0%)	1108 (58.7%)	1
Single	140 (7.4%)	147 (7.8%)	0.96 (0.75–1.24)	0.77
Widowed	611 (32.3%)	607 (32.1%)	1.02 (0.87–1.20)	0.82
Separated/Divorced	44 (2.3%)	27 (1.4%)	1.66 (1.01–2.70)	0.04
Educational level
Without or primary	1378 (73.5%)	1308 (70.3%)	1
Secondary or higher	498 (26.5%)	553 (29.7%)	0.81 (0.69–0.95)	0.01
Household size
Live alone	339 (17.9%)	363 (19.2%)	1
Live with cohabitant	1555 (82.1%)	1526 (80.8%)	1.09 (0.93–1.29)	0.29
Barthel index
0–90	766 (40.4%)	773 (40.8%)	0.98 (0.85–1.13)	0.80
>90	1129 (59.6%)	1122 (59.2%)	1
Smoking status
Non smoker	838 (44.2%)	983 (51.9%)	1
Smoker	165 (8.7%)	145 (7.7%)	1.73 (1.31–2.27)	<0.01
Ex-smoker	892 (47.1%)	767 (40.5%)	1.78 (1.48–2.14)	<0.01
High alcohol consumption
Yes	71 (3.7%)	54 (2.8%)	1.34 (0.93–1.93)	0.12
No	1824 (96.3%)	1841 (97.2%)	1
No. of hospital visits
0–2	922 (48.9%)	897 (47.8%)	1
≥3	962 (51.1%)	978 (52.2%)	0.95 (0.82–1.10)	0.50
Risk medical conditions
No	193 (10.2%)	255 (13.5%)	1
Yes	1702 (89.8%)	1640 (86.5%)	1.38 (1.13–1.69)	0.002
Epidemiologic week
Yes	1302 (68.7%)	1266 (66.8%)	1.92 (1.31–2.83)	0.001
No	593 (31.3%)	629 (33.2%)	1
Influenza vaccine
Yes	891 (47.0%)	855 (45.1%)	1.10 (0.95–1.27)	0.19
No	1004 (53.0%)	1040 (54.9%)	1
Pneumococcal polysaccharide vaccine in 5 previous years
Yes	259 (13.7%)	272 (14.4%)	0.94 (0.78–1.14)	0.53
No	1636 (86.3%)	1623 (85.6%)	1