Comparison 14. Influenza vaccines versus no vaccination: case‐control studies in community.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
14.1 Hospitalisations for influenza or pneumonia	2	1074	Odds Ratio (M‐H, Random, 95% CI)	0.89 [0.69, 1.15]
14.1.1 Outbreak ‐ vaccine matching (circulating strains)	0	0	Odds Ratio (M‐H, Random, 95% CI)	Not estimable
14.1.2 Outbreak ‐ vaccine matching absent or unknown	1	825	Odds Ratio (M‐H, Random, 95% CI)	0.92 [0.69, 1.22]
14.1.3 No outbreak ‐ vaccine matching	1	249	Odds Ratio (M‐H, Random, 95% CI)	0.82 [0.48, 1.40]
14.2 Hospitalisations for any respiratory disease	4	21378	Odds Ratio (M‐H, Random, 95% CI)	1.08 [0.95, 1.23]
14.2.1 Outbreak ‐ vaccine matching	3	20582	Odds Ratio (M‐H, Random, 95% CI)	1.08 [0.92, 1.26]
14.2.2 No outbreak ‐ not matching	1	796	Odds Ratio (M‐H, Random, 95% CI)	1.02 [0.68, 1.52]
14.3 Deaths from influenza or pneumonia	1	1092	Odds Ratio (M‐H, Random, 95% CI)	0.74 [0.53, 1.04]
14.3.1 Outbreak ‐ vaccine matching	1	1092	Odds Ratio (M‐H, Random, 95% CI)	0.74 [0.53, 1.04]
14.4 Pneumonia (no better defined)	1	519	Odds Ratio (M‐H, Fixed, 95% CI)	0.87 [0.57, 1.33]
14.4.1 Outbreak ‐ partially matching	1	519	Odds Ratio (M‐H, Fixed, 95% CI)	0.87 [0.57, 1.33]