Table 2. Interim adjusted seasonal vaccine effectiveness against any laboratory-confirmed influenza, influenza A(H1N1)pdm09, A(H3N2) and B, by age group, target group for vaccination and by study, Europe, influenza season 2017/18.

Influenza type/subtype and study site	Setting	Study population	Cases			Controls			Adjusted VE	95% CI
			All	Vacc	%	All	Vacc	%
Influenza A + B
ES	PC	All ages	1,452	98	7	947	75	8	52	29 to 67
		0–14 years	589	15	3	370	13	4	78	45 to 91
		15–64 years	762	44	6	511	40	8	54	23 to 73
		≥ 65 years	101	42	42	66	22	33	21	−93 to 68
		Target groupa	278	72	26	180	50	28	40	1 to 63
UK	PC	All ages	421	93	22	910	190	21	25	−10 to 48
		2–17 years (LAIV4)	69	5	7	166	19	11	53	−56 to 86
		≥ 18 years (IIV)	347	87	25	630	163	26	18	−23 to 45
EU-PC	PC	All ages	2,103	210	10	2,549	272	11	38	20 to 52
		0–17 years	846	26	3	998	35	4	59	23 to 78
		18–64 years	1,021	74	7	1,288	109	8	34	5 to 54
		≥ 65 years	234	110	47	262	128	49	44	8 to 66
		Target groupa	554	172	31	713	217	30	36	13 to 53
DK	PC and hospital	All ages	3,011	593	20	8,896	2299	26	34	25 to 41
		18–64 years	1,564	136	9	3,462	538	16	47	35 to 58
		≥ 65 years	934	447	48	3,089	1,688	55	23	10 to 34
EU-H	Hospital	≥ 65 years	385	200	52	546	332	61	35	13 to 51
Influenza A(H1N1)pdm09
EU-PC	PC	All ages	444	14	3	1,999	195	10	68	42 to 83
		18–64 years	203	7	3	955	77	8	63	12 to 84
DK	PC and hospital	All ages	214	18	8	8,896	2299	26	55	23 to 74
		18–64 years	119	7	6	3,462	538	16	60	13 to 82
		≥ 65 years	26	11	42	3,089	1,688	55	37	−40 to 72
Influenza A(H3N2)
ES	PC	All ages	233	22	9	947	75	8	7	−74 to 51
UK	PC	All ages	194	58	30	910	190	21	−27	−111 to 24
EU-PC	PC	All ages	220	35	16	1,505	147	10	−16	−96 to 31
		18–64 years	140	9	6	771	66	9	27	−62 to 67
DK	PC and hospital	All ages	122	53	43	8,896	2,299	26	-42	−116 to 7
		18–64 years	45	6	13	3,462	538	16	21	−95 to 68
		≥ 65 years	67	45	67	3,089	1,688	55	−65	−178 to 2
EU-H	Hospital	≥ 65 years	60	38	63	242	154	64	−1	−93 to 47
Any influenza B
ES	PC	All ages	1,022	72	7	947	75	8	52	27 to 68
		0–17 years	440	10	2	370	13	4	83	54 to 94
		18–64 years	503	31	6	511	40	8	51	13 to 72
		≥ 65 years	79	31	39	66	22	33	15	−114 to 66
		Target groupa	207	53	26	180	50	28	38	−5 to 63
UK	PC	All ages	209	33	16	910	190	21	54	24 to 72
EU-PC	PC	All ages	1,368	150	11	2,510	269	11	39	19 to 54
		0–17 years	562	21	4	980	35	4	58	15 to 79
		18–64 years	643	55	9	1,279	108	8	27	−9 to 51
		≥ 65 years	161	74	46	250	126	50	54	20 to 73
		Target groupa	382	125	33	696	215	31	39	14 to 56
DK	PC and hospital	All ages	2,298	437	19	8,896	2,299	26	36	27 to 44
		18–64 years	1,220	111	9	3,462	538	16	44	30 to 56
		≥ 65 years	701	319	46	3,089	1,688	55	28	14 to 39
EU-H	Hospital	≥ 65 years	249	131	53	524	321	61	34	8 to 52
Influenza B/Yamagata
ES	PC	All ages	84	4	5	993	81	8	77	14 to 94
EU-PCb	PC	All ages	395	34	9	2,065	206	10	49	19 to 67

CI: confidence interval; DK: Denmark study; ES: Spain study; EU-H: European hospital-based multi-country I-MOVE+ study; EU-PC: European primary care-based multi-country I-MOVE/I-MOVE+ study; PC: primary care; UK: United Kingdom study; Vacc: vaccinated; VE: vaccine effectiveness.

^a Groups targeted by seasonal influenza vaccination as defined locally in the studies and study sites.

^b Only includes study sites where lineage was available for all samples or where lineage was determined systematically.

Study sites included in the EU-H analysis: France, Italy, Navarra, the Netherlands, Portugal and Spain (except for influenza A(H3N2) analysis: Navarra and Spain only).

Study sites included in EU-PC analysis for all influenza and influenza B: Croatia, France, Germany, Ireland, Italy, the Netherlands, Portugal, Spain, Sweden. For analysis against A(H1N1)pdm09: France, Germany, Italy and Spain were included. For analysis against A(H3N2): France, Germany, Ireland, Spain and Sweden were included.