Table 3.
Efficacy of maternal inactivated influenza vaccine on episodes of PCR-confirmed influenza in women vaccinated at any time prepartum
|
Intervention |
Control |
Incidence rate ratio (95% CI) | Vaccine efficacy, % (95% CI) | p value | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cases | Person-time* | Incidence, per 1000 person-years | Cases | Person-time* | Incidence, per 1000 person-years | |||||
| Cumulative episodes | ||||||||||
| ≤2 months after vaccination | ||||||||||
| Nepal | 9 | 307·8 | 29·2 | 12 | 307·7 | 39·0 | 0·75 (0·32 to 1·78) | 25 (−78 to 68) | 0·51 | |
| Mali | 6 | 350·1 | 17·1 | 19 | 346·7 | 54·8 | 0·31 (0·12 to 0·79) | 69 (21 to 88) | 0·01 | |
| South Africa | 8 | 175·8 | 45·5 | 14 | 173·5 | 80·7 | 0·56 (0·24 to 1·34) | 44 (−34 to 76) | 0·20 | |
| Pooled | 23 | 833·7 | 27·6 | 45 | 827·9 | 54·4 | 0·51 (0·31 to 0·84) | 49 (16 to 69) | 0·01 | |
| ≤4 months after vaccination | ||||||||||
| Nepal | 20 | 615·7 | 32·5 | 22 | 615·3 | 35·8 | 0·91 (0·50 to 1·66) | 9 (−66 to 50) | 0·76 | |
| Mali | 7 | 694·1 | 10·0 | 26 | 688·0 | 37·8 | 0·27 (0·12 to 0·61) | 73 (39 to 88) | 0·002 | |
| South Africa | 16 | 347·2 | 46·1 | 28 | 343·6 | 81·5 | 0·56 (0·30 to 1·04) | 44 (−4 to 70) | 0·07 | |
| Pooled | 43 | 1657·0 | 26·0 | 76 | 1647·0 | 46·1 | 0·56 (0·39 to 0·82) | 44 (18 to 61) | 0·003 | |
| ≤6 months after vaccination | ||||||||||
| Nepal | 26 | 910·2 | 28·6 | 30 | 909·7 | 33·0 | 0·87 (0·51 to 1·46) | 13 (−46 to 49) | 0·59 | |
| Mali | 9 | 1012·6 | 8·9 | 37 | 1004·9 | 36·8 | 0·24 (0·12 to 0·50) | 76 (50 to 88) | <0·001 | |
| South Africa | 18 | 494·5 | 36·4 | 36 | 490·2 | 73·4 | 0·50 (0·28 to 0·87) | 50 (13 to 72) | 0·02 | |
| Pooled | 53 | 2417·2 | 21·9 | 103 | 2404·8 | 42·8 | 0·51 (0·37 to 0·71) | 49 (29 to 63) | <0·001 | |
| Non-cumulative episodes | ||||||||||
| ≤2 months after vaccination | ||||||||||
| Nepal | 9 | 307·8 | 29·2 | 12 | 307·7 | 39·0 | 0·75 (0·32 to 1·78) | 25 (−78 to 68) | 0·51 | |
| Mali | 6 | 350·1 | 17·1 | 19 | 346·5 | 54·8 | 0·31 (0·12 to 0·78) | 69 (22 to 88) | 0·01 | |
| South Africa | 8 | 175·8 | 45·5 | 14 | 173·5 | 80·7 | 0·56 (0·24 to 1·34) | 44 (−34 to 76) | 0·20 | |
| Pooled | 23 | 833·7 | 27·6 | 45 | 827·9 | 54·4 | 0·51 (0·31 to 0·84) | 49 (16 to 69) | 0·01 | |
| >2–4 months after vaccination | ||||||||||
| Nepal | 11 | 307·8 | 35·7 | 10 | 307·6 | 32·5 | 1·10 (0·47 to 2·59) | −10 (−159 to 53) | 0·83 | |
| Mali | 1 | 344·0 | 2·9 | 7 | 341·4 | 20·5 | 0·14 (0·02 to 1·15) | 86 (−15 to 98) | 0·07 | |
| South Africa | 8 | 171·4 | 46·6 | 14 | 170·1 | 82·3 | 0·57 (0·24 to 1·35) | 43 (−35 to 76) | 0·20 | |
| Pooled | 20 | 823·3 | 24·3 | 31 | 819·1 | 37·8 | 0·64 (0·36 to 1·12) | 36 (−12 to 64) | 0·12 | |
| >4–6 months after vaccination | ||||||||||
| Nepal | 6 | 294·6 | 20·4 | 8 | 294·4 | 27·2 | 0·75 (0·26 to 2·16) | 25 (−116 to 74) | 0·59 | |
| Mali | 2 | 318·4 | 6·0 | 11 | 316·8 | 33·3 | 0·18 (0·04 to 0·82) | 81 (18 to 96) | 0·03 | |
| South Africa | 2 | 147·2 | 13·6 | 8 | 146·6 | 54·6 | 0·25 (0·05 to 1·17) | 75 (−17 to 95) | 0·08 | |
| Pooled | 10 | 760·2 | 13·2 | 27 | 757·8 | 35·6 | 0·37 (0·18 to 0·76) | 63 (24 to 82) | 0·01 | |
Women might have had repeat episodes of influenza.
*
Person-time was calculated consistently across sites and might be different from original site publication.