Comparison 2. Influenza vaccines versus placebo: randomised controlled trials ‐ parenteral vaccine ‐ adverse events.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
2.1 General malaise	4	2560	Risk Ratio (M‐H, Random, 95% CI)	1.18 [0.87, 1.61]
2.2 Nausea	1	672	Risk Ratio (M‐H, Random, 95% CI)	1.75 [0.74, 4.12]
2.3 Upper respiratory tract symptoms	2	713	Risk Ratio (M‐H, Random, 95% CI)	1.35 [0.90, 2.01]
2.4 Headache	3	2519	Risk Ratio (M‐H, Random, 95% CI)	1.10 [0.76, 1.58]
2.5 Fever	3	2519	Risk Ratio (M‐H, Random, 95% CI)	1.57 [0.92, 2.71]
2.6 Local tenderness/sore arm	4	2560	Risk Ratio (M‐H, Random, 95% CI)	3.56 [2.61, 4.87]
2.7 Swelling ‐ erythema ‐ induration	2	1847	Risk Ratio (M‐H, Random, 95% CI)	8.23 [3.98, 17.05]