Influenza epidemiology and influenza vaccine effectiveness during the 2014–2015 season: annual report from the Global Influenza Hospital Surveillance Network

Table 6 IVE for all cases and for targeted groups only by age and strain

			Influenza-positive		Influenza-negative		Crude IVE		Adjusted IVE
Population	Strain	Age	Total	Vaccinated	Total	Vaccinated	Percent (95 % CI)	P interaction	Percent (95 % CI)	P interaction
Overall	Any	Any	2027	446	6428	1556	-1 (-17, 12)		22 (8, 33)
		<65 y	1334	78	4299	289	-4 (-36, 20)	0.090	-5 (-38, 20)	0.054
		≥65 y	693	368	2129	1267	21 (5, 34)	0.090	24 (9, 37)	0.054
	A(H3N2)	Any	1165	356	6428	1556	-6 (-24, 10)		20 (4, 33)
		<65 y	630	50	4299	289	-15 (-59, 17)	0.036	-16 (-64, 17)	0.031
		≥65 y	535	306	2129	1267	24 (7, 37)	0.036	25 (8, 39)	0.031
	A(H1N1)	Any	104	7	6428	1556	25 (-85, 69)		27 (-82, 71)
		<65 y	91	3	4299	289	16 (-173, 74)	0.996	21 (-161, 76)	0.993
		≥65 y	13	4	2129	1267	47 (-128, 88)	0.996	59 (-83, 91)	0.993
	B/Yamagata	Any	625	57	6428	1556	16 (-17, 39)		31 (2, 52)
		<65 y	509	20	4299	289	7 (-51, 42)	0.266	29 (-17, 58)	0.273
		≥65 y	116	37	2129	1267	38 (-2, 62	0.266	33 (-12, 61)	0.273
Targeted groups only	Any	Any	1670	425	5077	1462	13 (-2, 26)		23 (8, 35)
		<65 y	977	57	2948	195	-21 (-70. 14)	0.037	-12 (-58, 20)	0.019
		≥65 y	693	368	2129	1267	26 (16, 42)	0.037	28 (14, 41)	0.019
	H3N2	Any	994	344	5077	1462	13 (-4, 28)		22 (5, 36)
		<65 y	459	38	2948	195	-12 (-65, 24)	0.051	-20 (-80. 21)	0.030
		≥65 y	535	306	2129	1267	27 (11, 41)	0.051	28 (11, 42)	0.030
	H1N1	Any	84	6	5077	1462	44 (-58, 80)		46 (-52, 81)
		<65 y	71	2	2948	195	33 (-198, 85)	0.793	39 (-167, 86)	0.770
		≥65 y	13	4	2129	1267	47 (-128, 88)	0.793	50 (-111, 89)	0.770
	B/Yamagata	Any	486	49	5077	1462	21 (-18, 46)		30 (-5, 53)
		<65 y	370	12	2948	195	-8 (-105, 44)	0.139	8 (-79, 53)	0.250
		≥65 y	116	37	2129	1267	38 (-2, 62)	0.139	33 (-12, 60)	0.250

ISSN: 1471-2458