Table 4.

Efficacy of maternal inactivated influenza vaccine on episodes of PCR-confirmed influenza in infants and women by gestational age

		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
Infants
<29 weeks gestational age
	Nepal	62	709·0	87·4	90	722·5	124·6	0·70 (0·51 to 0·97)	30 (3 to 49)	0·03
	Mali	8	135·0	59·2	16	135·4	118·2	0·50 (0·21 to 1·17)	50 (−17 to 79)	0·11
	South Africa	7	289·8	24·2	12	282·7	42·4	0·57 (0·22 to 1·44)	43 (−44 to 78)	0·24
	Pooled	77	1153·2	66·8	118	1156·3	102·0	0·66 (0·49 to 0·88)	34 (12 to 51)	0·004
≥29 weeks gestational age
	Nepal	12	163·2	73·5	15	155·9	96·2	0·76 (0·36 to 1·63)	24 (−63 to 64)	0·49
	Mali	42	796·0	52·8	61	793·7	76·8	0·69 (0·46 to 1·02)	31 (−2 to 54)	0·06
	South Africa	12	178·8	67·1	25	184·1	135·8	0·49 (0·25 to 0·98)	51 (2 to 75)	0·04
	Pooled	66	1143·3	57·7	101	1139·4	88·6	0·65 (0·48 to 0·89)	35 (11 to 52)	0·01
Mothers
<29 weeks gestational age
	Nepal	27	1243·2	21·7	40	1246·2	32·1	0·68 (0·42 to 1·10)	32 (−10 to 58)	0·12
	Mali	4	207·6	19·3	5	206·6	24·2	0·80 (0·21 to 2·97)	20 (−197 to 79)	0·73
	South Africa	14	476·3	29·4	19	460·4	41·3	0·71 (0·36 to 1·42)	29 (−42 to 64)	0·34
	Pooled	45	1928·0	23·3	64	1914·2	33·4	0·70 (0·48 to 1·02)	30 (−2 to 52)	0·06
≥29 weeks gestational age
	Nepal	4	227·1	17·6	4	218·1	18·3	0·96 (0·24 to 3·84)	4 (−284 to 76)	0·95
	Mali	8	1052·0	7·6	36	1047·2	34·4	0·22 (0·10 to 0·48)	78 (52 to 90)	<0·001
	South Africa	5	231·2	21·6	19	240·4	79·0	0·27 (0·10 to 0·73)	73 (27 to 90)	0·01
	Pooled	17	1510·3	11·2	59	1506·9	39·2	0·29 (0·17 to 0·50)	71 (50 to 83)	<0·001

Women and infants could have had repeat episodes of influenza.