Table 2. Pooled adjusted seasonal vaccine effectiveness against influenza A(H3N2), overall, by age groups, by clade and genetic variants, I-MOVE primary care multicentre study, Europe, influenza season 2018/19 (n = 5,802).

Age group	Outcome	n	Cases		Controls		Adjusted VE (%)	95% CI (%)
			All	Vaccinated	All	Vaccinated
All ages	A(H3N2)	5,802	1,917	265	3,885	485	−1	−24 to 18
0–14 years		2,008	668	33	1,340	62	46	8–68
15–64 years		3,153	1,038	123	2,115	194	−26	−66 to 4
≥ 65 years		641	211	109	430	229	20	−20 to 46
All ages	A(H3N2) clade 3C.2a1b	3,217	334	55	2,883	375	28	−7 to 51
15–64 years		1,799	211	26	1,588	159	15	−43 to 50
All ages	A(H3N2) clade 3C.2a1b + T131Ka	2,582	131	15	2,451	329	57	16–78
15–64 years		1,468	81	7	1,387	141	51	−21 to 80
All ages	A(H3N2) clade 3C.2a1b + T135Ka	2,764	203	40	2,561	342	7	−52 to 43
15–64 years		1,515	130	19	1,385	145	−7	−102 to 43
All ages	A(H3N2) clade 3C.3a	2,000	201	35	1,799	270	−42	−137 to 15
0–14 years		715	97	8	618	41	42	−58 to 78
15–64 years		1,082	84	12	998	115	−74	−259 to 6

^a Positions 131 and 135 are in antigenic site A in the influenza haemagglutinin.

CI: confidence interval; VE: vaccine effectiveness.