Comparison 6.

Inactivated vaccine versus placebo (RCTs)

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Influenza	5	1628	Risk Ratio (M‐H, Random, 95% CI)	0.36 [0.28, 0.48]
1.1 Inactivated vaccines (one‐dose)	5	1628	Risk Ratio (M‐H, Random, 95% CI)	0.36 [0.28, 0.48]
1.2 Inactivated vaccines (two‐doses)	0	0	Risk Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
2 Influenza‐like illness	4	19044	Risk Ratio (M‐H, Random, 95% CI)	0.72 [0.65, 0.79]
2.1 Inactivated vaccines (one‐dose)	2	267	Risk Ratio (M‐H, Random, 95% CI)	0.35 [0.15, 0.81]
2.2 Inactivated vaccines (two‐doses)	2	18777	Risk Ratio (M‐H, Random, 95% CI)	0.72 [0.69, 0.76]