Comparison 3. Inactivated aerosol influenza vaccine versus placebo or 'do nothing'.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Influenza	1	1348	Odds Ratio (M‐H, Random, 95% CI)	0.38 [0.14, 1.02]
1.1 WHO recommended ‐ vaccine matching absent or unknown	1	1348	Odds Ratio (M‐H, Random, 95% CI)	0.38 [0.14, 1.02]
1.2 WHO recommended ‐ matching vaccine	0	0	Odds Ratio (M‐H, Random, 95% CI)	0.0 [0.0, 0.0]
2 Local harms	3	1578	Risk Ratio (M‐H, Random, 95% CI)	0.95 [0.71, 1.27]
2.1 Local ‐ sore throat	3	1500	Risk Ratio (M‐H, Random, 95% CI)	0.85 [0.54, 1.33]
2.2 Local ‐ combined endpoint (any or highest symptom)	1	78	Risk Ratio (M‐H, Random, 95% CI)	1.03 [0.71, 1.48]
3 Systemic harms	3	1880	Risk Ratio (M‐H, Random, 95% CI)	1.07 [0.71, 1.62]
3.1 Systemic ‐ myalgia	2	151	Risk Ratio (M‐H, Random, 95% CI)	0.90 [0.36, 2.25]
3.2 Systemic ‐ fatigue or indisposition	2	151	Risk Ratio (M‐H, Random, 95% CI)	1.40 [0.52, 3.75]
3.3 Systemic ‐ headache	2	151	Risk Ratio (M‐H, Random, 95% CI)	1.52 [0.85, 2.72]
3.4 Systemic ‐ fever	1	1349	Risk Ratio (M‐H, Random, 95% CI)	0.49 [0.03, 7.80]
3.5 Systemic ‐ combined endpoint (any or highest symptom)	1	78	Risk Ratio (M‐H, Random, 95% CI)	0.36 [0.12, 1.04]