Table 1.
Efficacy of maternal inactivated influenza vaccine on episodes of PCR-confirmed influenza in infants born to 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 infant-years | Cases | Person-time* | Incidence, per 1000 infant-years | |||||
| Cumulative episodes | ||||||||||
| ≤2 months of age | ||||||||||
| Nepal | 20 | 303·4 | 65·9 | 31 | 304·4 | 101·8 | 0·65 (0·37 to 1·14) | 35% (−14 to 63) | 0·13 | |
| Mali | 2 | 332·3 | 6·0 | 10 | 329·9 | 30·3 | 0·20 (0·04 to 0·91) | 80% (19 to 96) | 0·04 | |
| South Africa | 2 | 168·3 | 11·9 | 13 | 167·8 | 77·5 | 0·15 (0·03 to 0·68) | 85% (32 to 97) | 0·01 | |
| Pooled | 24 | 804·0 | 29·8 | 54 | 802·1 | 67·3 | 0·44 (0·27 to 0·72) | 56% (28 to 73) | 0·001 | |
| ≤4 months of age | ||||||||||
| Nepal | 43 | 606·7 | 70·9 | 61 | 608·7 | 100·2 | 0·71 (0·48 to 1·04) | 29% (−4 to 52) | 0·08 | |
| Mali | 11 | 651·2 | 16·9 | 35 | 649·4 | 53·9 | 0·31 (0·16 to 0·62) | 69% (38 to 84) | 0·001 | |
| South Africa | 14 | 334·2 | 41·9 | 30 | 333·3 | 90·0 | 0·46 (0·25 to 0·87) | 54% (13 to 75) | 0·02 | |
| Pooled | 68 | 1592·1 | 42·7 | 126 | 1591·3 | 79·2 | 0·54 (0·40 to 0·72) | 46% (28 to 60) | <0·001 | |
| ≤6 months of age | ||||||||||
| Nepal | 74 | 896·9 | 82·5 | 105 | 899·9 | 116·7 | 0·71 (0·52 to 0·95) | 29% (5 to 48) | 0·02 | |
| Mali | 50 | 931·0 | 53·7 | 77 | 929·0 | 82·9 | 0·65 (0·45 to 0·92) | 35% (8 to 55) | 0·02 | |
| South Africa | 19 | 468·6 | 40·6 | 37 | 466·8 | 79·3 | 0·51 (0·30 to 0·88) | 49% (12 to 70) | 0·02 | |
| Pooled | 143 | 2296·4 | 62·3 | 219 | 2295·7 | 95·4 | 0·65 (0·53 to 0·81) | 35% (19 to 47) | <0·001 | |
| Non-cumulative episodes | ||||||||||
| ≤2 months of age | ||||||||||
| Nepal | 20 | 303·4 | 65·9 | 31 | 304·4 | 101·8 | 0·65 (0·37 to 1·14) | 35 (−14 to 63) | 0·13 | |
| Mali | 2 | 332·3 | 6·0 | 10 | 329·9 | 30·3 | 0·20 (0·04 to 0·91) | 80 (19 to 96) | 0·04 | |
| South Africa | 2 | 168·3 | 11·9 | 13 | 167·8 | 77·5 | 0·15 (0·03 to 0·68) | 85 (32 to 97) | 0·01 | |
| Pooled | 24 | 804·0 | 29·8 | 54 | 802·1 | 67·3 | 0·44 (0·27 to 0·72) | 56 (28 to 73) | 0·001 | |
| >2–4 months of age | ||||||||||
| Nepal | 23 | 303·3 | 75·8 | 30 | 304·3 | 98·6 | 0·77 (0·45 to 1·32) | 23 (−32 to 55) | 0·34 | |
| Mali | 9 | 318·9 | 28·2 | 25 | 319·4 | 78·3 | 0·36 (0·17 to 0·77) | 64 (23 to 83) | 0·01 | |
| South Africa | 12 | 165·9 | 72·3 | 17 | 165·4 | 10·3 | 0·70 (0·34 to 1·47) | 30 (−47 to 66) | 0·35 | |
| Pooled | 44 | 788·1 | 55·8 | 72 | 789·2 | 91·2 | 0·61 (0·42 to 0·89) | 39 (11 to 58) | 0·01 | |
| >4–6 months of age | ||||||||||
| Nepal | 31 | 290·2 | 106·8 | 44 | 291·2 | 151·1 | 0·71 (0·45 to 1·12) | 29 (−12 to 55) | 0·14 | |
| Mali | 39 | 279·7 | 13·9 | 42 | 279·6 | 15·0 | 0·93 (0·60 to 1·44) | 7 (−44 to 40) | 0·74 | |
| South Africa | 5 | 134·3 | 37·2 | 7 | 133·5 | 52·4 | 0·71 (0·22 to 2·24) | 29 (−124 to 78) | 0·56 | |
| Pooled | 75 | 704·3 | 106·5 | 93 | 704·4 | 132·0 | 0·81 (0·60 to 1·09) | 19 (−9 to 40) | 0·17 | |
Infants might have had repeat episodes of influenza.
*
Person-time was calculated consistently across sites and might be different from original site publication.