Table 2. Characteristic of cases and controls, I-MOVE-COVID-19 and VEBIS hospital vaccine effectiveness studies, Europe, SARS-CoV-2 Alpha and Delta periods March–December 2021 (n = 4,736).
| Patient characteristic | Alpha period: January to June 2021 (n = 1,625) | Delta period: July to December 2021 (n = 3,111) | ||||||
|---|---|---|---|---|---|---|---|---|
| SARS-CoV-2 cases (n = 1,087) | Test-negative controls (n = 538) | SARS-CoV-2 cases (n = 1,669) | Test-negative controls (n = 1,442) | |||||
| Number | % | Number | % | Number | % | Number | % | |
| Median age (years) | 69 | 76 | 63 | 72 | ||||
| Age groups (years) | ||||||||
| 20–59 | 247 | 22.7 | 69 | 12.8 | 695 | 41.6 | 348 | 24.1 |
| 60–79 | 591 | 54.4 | 251 | 46.7 | 644 | 38.6 | 641 | 44.5 |
| ≥ 80 | 249 | 22.9 | 218 | 40.5 | 330 | 19.8 | 453 | 31.4 |
| Sex | ||||||||
| Male | 622 | 57.2 | 292 | 54.3 | 984 | 59.0 | 815 | 56.5 |
| Female | 465 | 42.8 | 246 | 45.7 | 685 | 41.0 | 627 | 43.5 |
| At least one chronic conditiona | ||||||||
| No | 481 | 44.3 | 139 | 25.8 | 929 | 55.7 | 449 | 31.1 |
| Yes | 606 | 55.7 | 399 | 74.2 | 740 | 44.3 | 993 | 68.9 |
| COVID-19 vaccination status | ||||||||
| Unvaccinated | 1,013 | 93.2 | 354 | 65.8 | 1,026 | 61.5 | 234 | 16.2 |
| Partial vaccination onlyb | 62 | 5.7 | 94 | 17.5 | 35 | 2.1 | 68 | 4.7 |
| Complete PSVc | 12 | 1.1 | 90 | 16.7 | 598 | 35.8 | 1,043 | 72.3 |
| Complete PSV + first boosterd | NA | 10 | 0.6 | 97 | 6.7 | |||
| Vaccine product among vaccinated: first dose | ||||||||
| Comirnaty | 45 | 61.6 | 145 | 80.6 | 392 | 61.0 | 886 | 73.4 |
| Vaxzevria | 21 | 28.8 | 19 | 10.6 | 156 | 24.3 | 178 | 14.7 |
| Spikevax | 7 | 9.6 | 15 | 8.3 | 22 | 3.4 | 90 | 7.5 |
| JCovden | 0 | 0.0 | 1 | 0.6 | 72 | 11.2 | 47 | 3.9 |
| Other/unknowne | 1 | NC | 4 | NC | 1 | NC | 7 | NC |
| Vaccine product among vaccinated: second dose | ||||||||
| Comirnaty | 12 | 100 | 82 | 92.1 | 381 | 71.1 | 852 | 78.0 |
| Vaxzevria | 0 | 0 | 0 | 0.0 | 135 | 25.2 | 155 | 14.2 |
| Spikevax | 0 | 0 | 7 | 7.9 | 20 | 3.7 | 81 | 7.4 |
| Other/unknowne | 0 | NC | 0 | NC | 0 | NC | 5 | NC |
| Vaccine product among vaccinated: first booster | ||||||||
| Comirnaty | NA | 10 | 100 | 89 | 91.8 | |||
| Spikevax | 0 | NC | 7 | 7.2 | ||||
| Other/unknowne | 0 | NC | 1 | 1.0 | ||||
| Severe outcomes | ||||||||
| Hospitalisation | 1,087 | 100 | 538 | 100 | 1,669 | 100 | 1,442 | 100 |
| ICU admission | 231 | 21.7 | 20 | 4.0 | 330 | 20.0 | 119 | 8.4 |
| No ICU admission | 835 | 78.3 | 482 | 96.0 | 1,317 | 80.0 | 1,295 | 91.6 |
| Missinge | 21 | NC | 36 | NC | 22 | NC | 28 | NC |
| In-hospital death | 181 | 19.0 | 27 | 8.7 | 195 | 12.6 | 92 | 7.3 |
| Discharged alive | 744 | 78.2 | 242 | 77.5 | 1,286 | 83.0 | 1,082 | 85.9 |
| Still in hospital/transferred | 27 | 2.8 | 43 | 13.8 | 69 | 4.4 | 85 | 6.8 |
| Missinge | 135 | NC | 226 | NC | 119 | NC | 183 | NC |
| Study site and countryf | ||||||||
| Belgium | 87 | 8.0 | 68 | 12.6 | 115 | 6.9 | 88 | 6.1 |
| Czechia | NI | NI | ||||||
| Spain | 236 | 21.7 | 110 | 20.5 | 379 | 22.7 | 400 | 27.7 |
| France | 39 | 3.6 | 14 | 2.6 | 197 | 11.8 | 136 | 9.4 |
| Germany | NI | NI | ||||||
| Greece | NI | NI | ||||||
| Croatia | 579 | 53.3 | 74 | 13.8 | 433 | 25.9 | 92 | 6.4 |
| Ireland | NI | 75 | 4.5 | 53 | 3.7 | |||
| Lithuania | 24 | 2.2 | 6 | 1.1 | 34 | 2.0 | 22 | 1.5 |
| Luxembourg | NI | NI | ||||||
| Malta | NI | 95 | 5.7 | 225 | 15.6 | |||
| Navarra, Spain | 37 | 3.4 | 85 | 15.8 | 42 | 2.5 | 109 | 7.6 |
| the Netherlands | 85 | 7.8 | 181 | 33.6 | 77 | 4.6 | 149 | 10.3 |
| Portugal | NI | 222 | 13.3 | 168 | 11.7 | |||
| Romania | NI | NI | ||||||
| All sites | 1,087 | 100 | 538 | 100 | 1,669 | 100 | 1,442 | 100 |
ICU: intensive care unit; I-MOVE: Influenza – Monitoring Vaccine Effectiveness in Europe; NA: not applicable; NC: not calculated; NI: no data included; PSV: primary series vaccination; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2; VEBIS: Vaccine Effectiveness, Burden and Impact Studies.
a At least one of four commonly collected conditions (diabetes, heart disease, lung disease, asthma).
b Partially vaccinated: any SARI patient who received only one of two recommended doses of a two-dose vaccine.
c Completely vaccinated: any SARI patient who received either both of two recommended doses of a two-dose vaccine, or a single dose of Jcovden.
d Vaccinated with first booster: any SARI patient who received either both of two recommended doses of a two-dose vaccine, or a single dose of Jcovden, plus one booster dose.
e Missing totals not included in percentages.
f Eight sites submitting data during the Alpha and five during the Delta period did not have sufficient eligible SARI patients for inclusion in these analyses (this table gives final numbers by site, after exclusions).