Comparison 15. Influenza vaccines versus no vaccination: case‐control studies in community ‐ adjusted rates.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
15.1 Hospitalisations for influenza or pneumonia	5		Odds Ratio (IV, Random, 95% CI)	0.59 [0.47, 0.74]
15.1.1 Epidemic ‐ vaccine matching	1		Odds Ratio (IV, Random, 95% CI)	0.55 [0.36, 0.85]
15.1.2 Non‐epidemic ‐ vaccine not matching	0		Odds Ratio (IV, Random, 95% CI)	Not estimable
15.1.3 Epidemic year ‐ vaccine matching absent or unknown	2		Odds Ratio (IV, Random, 95% CI)	0.68 [0.58, 0.79]
15.1.4 Non‐epidemic ‐ vaccine matching	2		Odds Ratio (IV, Random, 95% CI)	0.37 [0.16, 0.87]
15.2 Hospitalisations for any respiratory disease	3		Odds Ratio (IV, Random, 95% CI)	0.71 [0.56, 0.90]
15.2.1 Epidemic ‐ vaccine matching	3		Odds Ratio (IV, Random, 95% CI)	0.71 [0.56, 0.90]
15.2.2 Non‐epidemic ‐ vaccine matching	0		Odds Ratio (IV, Random, 95% CI)	Not estimable
15.2.3 Non‐epidemic year ‐ vaccine matching	0		Odds Ratio (IV, Random, 95% CI)	Not estimable
15.3 Deaths from pneumonia or influenza	2		Odds Ratio (IV, Random, 95% CI)	0.74 [0.60, 0.92]
15.3.1 Epidemic year ‐ vaccine matching	1		Odds Ratio (IV, Random, 95% CI)	0.76 [0.60, 0.97]
15.3.2 Epidemic year ‐ vaccine matching absent or unknown	1		Odds Ratio (IV, Random, 95% CI)	0.67 [0.42, 1.07]