Comparison 14. 1968 to 1969 pandemic: inactivated monovalent parenteral influenza vaccine versus placebo.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Influenza‐like illness	4	4580	Risk Ratio (M‐H, Random, 95% CI)	0.35 [0.25, 0.48]
1.1 WHO recommended parenteral ‐ matching vaccine ‐ 1 dose	4	4226	Risk Ratio (M‐H, Random, 95% CI)	0.35 [0.23, 0.53]
1.2 WHO recommended parenteral ‐ matching vaccine ‐ 2 doses	1	354	Risk Ratio (M‐H, Random, 95% CI)	0.35 [0.22, 0.57]
2 Influenza	1	1923	Risk Ratio (M‐H, Random, 95% CI)	0.07 [0.02, 0.31]
2.1 WHO recommended parenteral ‐ matching vaccine	1	1923	Risk Ratio (M‐H, Random, 95% CI)	0.07 [0.02, 0.31]
3 Hospitalisations	1	1923	Risk Ratio (M‐H, Random, 95% CI)	0.35 [0.13, 0.94]
3.1 WHO recommended parenteral ‐ matching vaccine	1	1923	Risk Ratio (M‐H, Random, 95% CI)	0.35 [0.13, 0.94]
4 Pneumonia	1	1923	Risk Ratio (M‐H, Random, 95% CI)	0.59 [0.05, 6.51]
4.1 WHO recommended parenteral ‐ matching vaccine	1	1923	Risk Ratio (M‐H, Random, 95% CI)	0.59 [0.05, 6.51]
5 Working days lost	1	1667	Mean Difference (IV, Random, 95% CI)	‐0.45 [‐0.60, ‐0.30]
5.1 WHO recommended parenteral ‐ matching vaccine	1	1667	Mean Difference (IV, Random, 95% CI)	‐0.45 [‐0.60, ‐0.30]
6 Days ill	1	1667	Mean Difference (IV, Random, 95% CI)	‐0.45 [‐0.60, ‐0.30]
6.1 WHO recommended ‐ matching vaccine	1	1667	Mean Difference (IV, Random, 95% CI)	‐0.45 [‐0.60, ‐0.30]