Comparison 5. Inactivated parenteral influenza vaccine versus placebo ‐ cohort studies.

Outcome or subgroup title	No. of studies	No. of participants	Statistical method	Effect size
1 Seasonal inactivated vaccine effectiveness in mothers ‐ pregnant women	4		Risk Ratio (M‐H, Random, 95% CI)	Subtotals only
1.1 H1N1 ‐ vaccine ‐ effectiveness ILI (unadjusted data)	1	7328	Risk Ratio (M‐H, Random, 95% CI)	0.11 [0.06, 0.21]
1.2 Seasonal ‐ vaccine ‐ effectiveness ILI ‐ (unadjusted data)	3	50507	Risk Ratio (M‐H, Random, 95% CI)	0.54 [0.24, 1.18]
2 Seasonal inactivated vaccine effectiveness in newborns ‐ pregnant women	2		Hazard Ratio (Random, 95% CI)	Subtotals only
2.1 Seasonal vaccine effectiveness ILI (HR adjusted data)	2		Hazard Ratio (Random, 95% CI)	0.96 [0.90, 1.03]
3 Seasonal inactivated vaccine effectiveness in newborns ‐ pregnant women	1		Risk Ratio (Random, 95% CI)	Subtotals only
3.1 Seasonal vaccine effectiveness ILI (RR adjusted data)	1		Risk Ratio (Random, 95% CI)	0.92 [0.73, 1.16]
3.2 Seasonal vaccine efficacy influenza ‐ laboratory‐confirmed	1		Risk Ratio (Random, 95% CI)	0.59 [0.37, 0.94]
4 H1N1 vaccine ‐ safety ‐ pregnancy‐related outcomes ‐ pregnant women	15		Odds Ratio (Random, 95% CI)	Subtotals only
4.1 Abortion (OR adjusted data)	5		Odds Ratio (Random, 95% CI)	0.75 [0.62, 0.90]
4.2 Abortion (HR adjusted data)	3		Odds Ratio (Random, 95% CI)	0.81 [0.63, 1.04]
4.3 Congenital malformation (OR adjusted data)	6		Odds Ratio (Random, 95% CI)	1.11 [0.99, 1.23]
4.4 Prematurity (< 37 weeks) (OR unadjusted data)	11		Odds Ratio (Random, 95% CI)	0.76 [0.67, 0.85]
4.5 Prematurity (< 37 weeks) (OR adjusted data)	7		Odds Ratio (Random, 95% CI)	0.84 [0.76, 0.93]
4.6 Prematurity (< 37 weeks) (HR adjusted data)	2		Odds Ratio (Random, 95% CI)	1.11 [0.46, 2.68]
4.7 Prematurity (< 37 weeks) vaccination in I trimester OR adjusted data	2		Odds Ratio (Random, 95% CI)	1.08 [0.92, 1.28]
4.8 Prematurity (< 37 weeks) vaccination in II/III trimester OR adjusted data	2		Odds Ratio (Random, 95% CI)	0.96 [0.87, 1.06]
4.9 Neonatal death (OR adjusted data)	2		Odds Ratio (Random, 95% CI)	1.09 [0.40, 2.95]
5 Seasonal vaccine ‐ safety ‐ pregnancy‐related outcomes ‐ pregnant women	7		Odds Ratio (Random, 95% CI)	Subtotals only
5.1 Abortion (OR unadjusted data)	1		Odds Ratio (Random, 95% CI)	0.60 [0.41, 0.86]
5.2 Congenital malformation (OR unadjusted data)	2		Odds Ratio (Random, 95% CI)	0.55 [0.08, 3.73]
5.3 Prematurity (OR unadjusted data)	6		Odds Ratio (Random, 95% CI)	0.95 [0.82, 1.10]
5.4 Prematurity (OR adjusted data)	2		Odds Ratio (Random, 95% CI)	0.93 [0.82, 1.06]
5.5 Neonatal death (OR unadjusted data)	1		Odds Ratio (Random, 95% CI)	0.55 [0.35, 0.88]
6 Seasonal vaccine containing H1N1	2		Risk Ratio (Random, 95% CI)	Subtotals only
6.1 Prematurity (37 weeks) vaccination in I trimester HR adjusted data	2		Risk Ratio (Random, 95% CI)	1.63 [0.76, 3.47]
6.2 Prematurity (< 37 weeks) vaccination in II trimester HR adjusted data	2		Risk Ratio (Random, 95% CI)	1.48 [0.21, 10.64]
6.3 Prematurity (< 37 weeks) vaccination in III trimester HR adjusted data	2		Risk Ratio (Random, 95% CI)	1.37 [0.44, 4.25]
6.4 Prematurity (< 37 weeks) vaccination at any time during pregnancy HR adjusted data	2		Risk Ratio (Random, 95% CI)	1.75 [0.57, 5.44]