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. 2023 May 25;28(21):2300116. doi: 10.2807/1560-7917.ES.2023.28.21.2300116

Table 2. Interim adjusted vaccine effectiveness (VE) against all laboratory-confirmed influenza, influenza A, A(H1N1)pdm09, A(H3N2) and B, by age group, target group for vaccination and by study, six European studies, influenza season 2022/23.

Influenza (sub)type and study Setting Study
populationa 		Cases Controls VEb 95% CI
All Vaccinated % All Vaccinated %
All influenza (A and B)c
EU-PC PC All ages 3,977 275 7 10,184 1,582 16 44 34 to 52
0–17 years 1,679 36 2 2,892 96 3 55 31 to 71
18–64 years 2,067 123 6 5,598 524 9 43 29 to 54
≥ 65 years 231 116 50 1,694 962 57 33 8 to 51
Target groupd 1,005 220 22 4,112 1,367 33 38 24 to 49
EN-EC EC All ≥ 18 years 3,046 1,158 38 7,797 3,722 48 30 21 to 38
2–17 years 714 116 16 1,501 389 26 61 50 to 70
18–64 years 1,667 315 19 2,954 798 27 36 22 to 48
≥ 65 years 1,379 843 61 4,843 2,924 60 28 16 to 38
EU-H H All ages 488 170 35 2,620 1,249 48 27 6 to 44
18–64 years 157 25 16 500 135 27 17 −44 to 52
≥ 65 years 279 143 51 1,597 1,086 68 29 4 to 47
Target groupd 378 161 43 1,959 1,212 62 31 9 to 48
SC-H H All ≥ 18 years 4,635 2,317 50 29,442 14,709 50 29 24 to 35
18–64 years 1,987 492 25 10,166 2,561 25 34 26 to 42
≥ 65 years 2,648 1,825 69 19,276 12,148 63 27 19 to 34
Influenza A (all)
DK-PC PC All ages 3,048 612 20 30,957 9,996 32 44 37 to 50
2–6 years 339 18 5 2,368 399 17 77 62 to 86
0–17 years 898 25 3 8,804 474 5 61 40 to 74
18–64 years 1,702 226 13 14,189 3,065 22 49 41 to 56
≥ 65 years 448 361 81 7,964 6,457 81 19 −4 to 37
EU-PC PC All ages 3,602 265 7 10,174 1,578 16 40 30 to 49
0–17 years 1,492 35 2 2,890 96 3 50 22 to 68
18–64 years 1,883 116 6 5,592 522 9 40 25 to 52
≥ 65 years 227 114 50 1,692 960 57 32 7 to 51
Target groupd 943 214 23 4,107 1,363 33 35 21 to 47
EN-EC EC All ≥ 18 years 2,969 1,152 39 7,797 3,722 48 29 20 to 37
2–17 years 680 114 17 1,501 389 26 60 48 to 69
18–64 years 1,596 312 20 2,954 798 27 35 20 to 46
≥ 65 years 1,373 840 61 4,843 2,924 60 27 16 to 38
DK-H H All ages 1,221 620 51 32,581 18,513 57 33 23 to 42
2–6 years 49 1 2 708 115 16 90 23 to 99
0–17 years 142 2 1 3,116 145 5 80 16 to 95
18–64 years 356 87 24 8,390 2,316 28 36 17 to 50
≥ 65 years 723 531 73 21,075 16,052 76 29 16 to 40
EU-H H All ages 468 166 35 2,611 1,245 48 27 6 to 44
18–64 years 146 24 16 498 134 27 12 −53 to 50
≥ 65 years 272 140 51 1,590 1,083 68 28 2 to 47
Target groupd 363 157 43 1,951 1,208 62 30 7 to 47
SC-H H All ≥ 18 years 4,601 2,310 50 29,381 14,671 50 29 23 to 34
18–64 years 1,961 489 25 10,141 2,552 25 34 25 to 42
≥ 65 years 2,640 1,821 69 19,240 12,119 63 26 18 to 33
Influenza A(H1N1)pdm09
DK-PC PC All ages 394 74 19 30,957 9,996 32 46 26 to 60
2–6 years 42 2 5 2,368 399 17 79 14 to 95
0–17 years 122 2 2 8,804 474 5 77 6 to 94
18–64 years 224 36 16 14,189 3,065 22 35 6 to 55
≥ 65 years 48 36 75 7,964 6,457 81 37 −22 to 67
EU-PC PC All agese 485 55 11 9,569 1,488 16 28 0 to 50
18–64 years 328 26 8 5,261 494 9 42 9 to 64
Target groupd 168 50 30 3,896 1,285 33 8 −39 to 39
EN-EC EN All ≥ 18 years 244 94 39 2,357 1,116 47 26 −9 to 50
2–17 years 65 9 14 660 134 20 49 −17 to 77
18–64 years 133 30 23 995 271 27 21 −44 to 57
≥ 65 years 111 64 58 1,362 845 62 28 −21 to 57
DK-H H All ages 135 64 47 32,581 18,513 57 34 1 to 56
18–64 years 45 13 29 8,390 2,316 28 22 −51 to 60
≥ 65 years 73 50 68 21,075 16,052 76 42 5 to 65
SC-H H All ≥ 18 years 290 116 40 29,435 14,707 50 42 24 to 56
18–64 years 142 23 16 10,161 2,561 25 56 19 to 73
≥ 65 years 148 93 63 19,274 12,146 63 31 −1 to 52
Influenza A(H3N2)
DK-PCc PC All ages 297 80 27 30,957 9,996 32 23 −7 to 45
18–64 years 163 24 15 14,189 3,065 22 36 1 to 59
EU-PC PC All agese 2,913 193 7 9,879 1,544 16 44 32 to 54
0–17 years 1,291 25 2 2,874 95 3 62 37 to 78
18–64 years 1,455 86 6 5,379 512 10 39 22 to 53
≥ 65 years 167 82 49 1,626 937 58 39 11 to 57
Target groupd 719 150 21 3,961 1,333 34 41 26 to 54
EN-EC EC All ≥ 18 years 288 104 36 2,357 1,116 47 37 12 to 55
2–17 years 144 17 12 660 134 20 70 46 to 84
18–64 years 145 28 19 995 271 27 42 −5 to 68
≥ 65 years 111 76 68 1,362 845 62 42 10 to 62
DK-H H All ages 115 65 57 32,581 18,513 57 2 −53 to 37
EU-H H All agesf 288 120 42 2,575 1,242 48 27 1 to 46
≥ 65 years 191 103 54 1,574 1,080 69 28 −3 to 49
Target groupd 238 114 48 1,929 1,205 62 26 −3 to 47
SC-H H All ≥ 18 years 479 152 32 29,381 14,703 50 32 16 to 45
18–64 years 188 42 22 10,164 2,559 25 36 7 to 56
≥ 65 years 291 203 70 19,272 12,144 63 33 12 to 49
Influenza B
DK-PC PC All ages 3,077 94 3 30,957 9,996 32 85 82 to 88
2–6 years 270 3 1 2,368 399 17 95 85 to 99
0–17 years 1,511 11 1 8,804 474 5 90 82 to 95
18–64 years 1,532 62 4 14,189 3,065 22 86 82 to 89
≥ 65 years 34 21 62 7,964 6,457 81 66 33 to 83
EU-PC PC All agese 368 10 3 8,601 1,388 16 64 32 to 83
0–17 years 190 1 1 2,638 93 4 90 52 to 100
18–64 years 177 8 5 4,553 448 10 51 1 to 79
EN-EC EC All ≥ 18 years 80 6 8 7,797 3,722 48 78 44 to 92
2–17 years 35 2 6 1,501 389 26 88 47 to 97
18–64 years 73 3 4 2,954 798 27 84 43 to 95
DK-H H All ages 301 39 13 32,581 18,513 57 73 61 to 82
2–6 years 35 1 3 708 115 16 87 6 to 98
0–17 years 132 1 1 3,116 145 5 89 19 to 98
18–64 years 125 11 9 8,390 2,316 28 78 59 to 88
≥ 65 years 44 27 61 21,075 16,052 76 58 22 to 77
SC-H PC All ≥ 18 years 34 7 21 29,410 14,702 50 50 −36 to 82

CI: confidence interval; DK-H: Denmark hospital study; DK-PC: Denmark primary care study; EC: Emergency care; EN-EC: England emergency care study; EU: European Union; EU-H: EU hospital multicentre VEBIS study; EU-PC: EU primary care multicentre VEBIS study; PC: primary care; SC-H: Scottish hospital study; VE: vaccine effectiveness; VEBIS: VE, Burden and Impact Studies.

a Age-specific or target group-specific VE was not included for overall or (sub)type-specific VE in some study sites, where sample size did not allow estimation of VE. Additionally for EU-PC: three study sites with < 10 A(H1N1)pdm09 cases were excluded from A(H1N1)pdm09 VE analysis (11 cases); two study sites with < 10 A(H3N2) cases were dropped from A(H3N2) VE analysis (8 cases); five study sites with < 10 B cases were not included in B VE analysis (8 cases).

b For details of adjustment variables, see Table 1.

c All influenza (A and B) estimates were not presented for DK-PC and DK-H due to difference in VE across influenza types.

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

e Three study sites with < 10 A(H1N1)pdm09 cases were excluded from A(H1N1)pdm09 VE analysis (11 cases); two study sites with < 10 A(H3N2) cases were dropped from A(H3N2) VE analysis (8 cases); five study sites with < 10 B cases were not included in B VE analysis (8 cases).

f Two study sites with < 10 influenza A(H3N2) cases were dropped from A(H3N2) VE analysis (10 cases).