Table 2.
Primary outcomes
| Cohort 1 | Cohort 2 | Combined | ||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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| Placebo | Vaccine | Risk ratio (95% CI) |
p value | Placebo | Vaccine | Risk ratio (95% CI) |
p value | Placebo | Vaccine | Risk ratio (95% CI) |
p value | |||||||
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| Cases* | Incidence† | Cases* | Incidence† | Cases* | Incidence† | Cases* | Incidence† | Cases* | Incidence† | Cases* | Incidence† | |||||||
| Maternal | ||||||||||||||||||
|
| ||||||||||||||||||
| All influenza-like illness | 166 (642·4) | 258·4 | 157 (665·0) | 236·1 | 0·91 (0·71–1·16) | 0·431 | 98 (455·6) | 215·1 | 62 (451·1) | 137·4 | 0·64 (0·45–0·91) | 0·014 | 264 (1098·0) | 240·4 | 219 (1116·1) | 196·2 | 0·81 (0·66–0·99) | 0·041 |
| Influenza-like illness (pregnancy) | 78 (261·7) | 298·0 | 66 (272·2) | 242·5 | 0·81 (0·58–1·14) | 0·226 | 50 (160·3) | 311·9 | 30 (161·2) | 186·1 | 0·60 (0·38–0·94) | 0·026 | 128 (422·0) | 303·3 | 96 (433·4) | 221·5 | 0·73 (0·56–0·96) | 0·022 |
| Influenza-like illness (postpartum) | 88 (380·7) | 231·1 | 91 (392·8) | 231·7 | 1·01 (0·73–1·41) | 0·950 | 48 (295·2) | 162·6 | 32 (289·9) | 110·4 | 0·68 (0·41–1·11) | 0·123 | 136 (676·0) | 201·2 | 123 (682·7) | 180·2 | 0·90 (0·68–1·18) | 0·446 |
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| Infant | ||||||||||||||||||
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| All laboratory-confirmed influenza | 69 (322·9) | 213·7 | 60 (335·2) | 179·0 | 0·84 (0·59–1·19) | 0·324 | 36 (256·2) | 140·5 | 14 (247·1) | 56·7 | 0·40 (0·22–0·74) | 0·003 | 105 (579·0) | 181·3 | 74 (582·3) | 127·1 | 0·70 (0·52–0·95) | 0·020 |
| Low birthweight (<2500 g) | 220 (28%) of 780 | NA | 193 of (23%) 807 | NA | 0·85 (0·72–1·00) | 0·052 | 145 (25%) of 581 | NA | 122 (21%) of 573 | NA | 0·85 (0·69–1·05) | 0·141 | 365 (27%) of 1361 | NA | 315 (23%) of 1380 | NA | 0·85 (0·75–0·97) | 0·016 |
*
Data are n (person-years) or n (%) of N for low birthweight.
†
Data are incidence per 1000 person-years.
NA=not applicable.