Comparison 3. Influenza vaccines versus placebo: randomised controlled trials ‐ inactivated aerosol vaccine.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
3.1 Influenza	1	176	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.40, 1.99]
3.1.1 Outbreak ‐ vaccine matching ‐ psychiatric hospital	1	176	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.40, 1.99]
3.2 Influenza‐like illness	1	176	Risk Ratio (M‐H, Random, 95% CI)	0.84 [0.41, 1.71]
3.2.1 Outbreak ‐ vaccine matching ‐ psychiatric hospital	1	176	Risk Ratio (M‐H, Random, 95% CI)	0.84 [0.41, 1.71]