Table 2.
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 | ||||
| During pregnancy† | |||||||||
| Nepal | 19 | 563·6 | 33·7 | 24 | 558·7 | 43·0 | 0·78 (0·43 to 1·43) | 22 (−43 to 57) | 0·43 |
| Mali | 6 | 313·7 | 19·1 | 18 | 312·2 | 57·7 | 0·33 (0·13 to 0·84) | 67 (16 to 87) | 0·02 |
| South Africa | 11 | 226·9 | 48·5 | 19 | 223·4 | 85·0 | 0·57 (0·27 to 1·20) | 43 (−20 to 73) | 0·14 |
| Pooled | 36 | 1104·2 | 32·6 | 61 | 1094·3 | 55·7 | 0·58 (0·39 to 0·88) | 42 (12 to 61) | 0·01 |
| After pregnancy† | |||||||||
| Nepal | 12 | 910·2 | 13·2 | 20 | 909·7 | 22·0 | 0·60 (0·29 to 1·23) | 40 (−23 to 71) | 0·16 |
| Mali | 7 | 973·5 | 7·2 | 23 | 966·3 | 23·8 | 0·30 (0·13 to 0·70) | 70 (30 to 87) | 0·01 |
| South Africa | 6 | 491·2 | 12·2 | 19 | 488·2 | 38·9 | 0·31 (0·12 to 0·78) | 69 (13 to 88) | 0·01 |
| Pooled | 25 | 2374·9 | 10·5 | 62 | 2364·3 | 26·2 | 0·40 (0·25 to 0·64) | 60 (36 to 75) | <0·001 |
| During full study period | |||||||||
| Nepal | 31 | 1471·3 | 21·1 | 44 | 1466·4 | 30·0 | 0·70 (0·44 to 1·11) | 30 (−12 to 56) | 0·13 |
| Mali | 12 | 1259·6 | 9·5 | 41 | 1253·8 | 32·7 | 0·29 (0·15 to 0·55) | 71 (45 to 85) | <0·001 |
| South Africa | 19 | 707·4 | 26·8 | 38 | 700·8 | 54·2 | 0·50 (0·28 to 0·86) | 50 (14 to 72) | 0·01 |
| Pooled | 62 | 3438·3 | 18·0 | 123 | 3421·0 | 36·0 | 0·50 (0·37 to 0·68) | 50 (32 to 63) | <0·001 |
Women might have had repeat episodes of influenza.
*
Person-time was calculated consistently across sites and might be different from original site publication.
†
Women without a date of delivery were excluded from the analyses.