Table 1.
Characteristics of analytical cohort, overall and by the Delta and the Omicron variants.
| Overall, N = 7,775a | Delta, W29–W49 2021 N = 5,512a | Omicron BA.1, W3–W5 2022 N = 1,120a | Omicron BA.4/5, W28–W41 2022 N = 1,143a | p-valueb | |
|---|---|---|---|---|---|
| Gender | < 0.001 | ||||
| Female | 3,623 (46.6%) | 2,483 (45.0%) | 517 (46.2%) | 623 (54.5%) | |
| Male | 4,152 (53.4%) | 3,029 (55.0%) | 603 (53.8%) | 520 (45.5%) | |
| Median age and interquartile range (in years) | 69 (55, 80) | 66 (53, 78) | 73 (60, 84) | 78 (66, 85.5) | < 0.001 |
| Age | < 0.001 | ||||
| 0–17 years | 347 (4.5%) | 118 (2.1%) | 86 (7.7%) | 143 (12.5%) | |
| 18–64 years | 2,830 (36.4%) | 2,438 (44.2%) | 268 (23.9%) | 124 (10.8%) | |
| 65–79 years | 2,471 (31.8%) | 1,752 (31.8%) | 372 (33.2%) | 347 (30.4%) | |
| ≥80 years | 2,127 (27.3%) | 1,204 (21.9%) | 394 (35.2%) | 529 (46.3%) | |
| Care home resident | < 0.001 | ||||
| Others | 7,402 (95.2%) | 5,367 (97.4%) | 994 (88.8%) | 1,041 (91.1%) | |
| Long term care residents | 373 (4.8%) | 145 (2.6%) | 126 (11.2%) | 102 (8.9%) | |
| Vaccination | < 0.001 | ||||
| Non-vaccinated | 5,022 (64.6%) | 3,915 (71.0%) | 670 (59.8%) | 437 (38.2%) | |
| Partially vaccinated | 114 (1.5%) | 81 (1.5%) | 27 (2.4%) | 6 (0.5%) | |
| Fully vaccinated | 1,973 (25.4%) | 1,500 (27.2%) | 277 (24.7%) | 196 (17.2%) | |
| Vaccinated with additional dose(s) | 666 (8.5%) | 16 (0.3%) | 146 (13.1%) | 504 (44.1%) | |
| Time since last vaccination (days) if vacc. completely or w. add. dose/-s | < 0.001 | ||||
| Non-vaccinated or partially vaccinated | 5,136 (66.1%) | 3,996 (72.5%) | 697 (62.2%) | 443 (38.8%) | |
| 14–180 days since last vaccination | 1,031 (13.3%) | 740 (13.4%) | 267 (23.8%) | 24 (2.1%) | |
| 181–270 days since last vaccination | 966 (12.4%) | 676 (12.3%) | 89 (8.0%) | 201 (17.6%) | |
| 271+ days since last vaccination | 642 (8.2%) | 100 (1.8%) | 67 (6.0%) | 475 (41.5%) | |
| Reinfection | < 0.001 | ||||
| Primary infection | 7,563 (97.3%) | 5,488 (99.6%) | 1,077 (96.2%) | 998 (87.3%) | |
| Reinfection | 212 (2.7%) | 24 (0.4%) | 43 (3.8%) | 145 (12.7%) | |
| Time since previous positive result (in days) | 352 (251, 574.5) | 301 (275.8, 329) | 403 (382, 439) | 324 (221, 610) | 0.012 |
| Charlson comorbidity index with original weights | < 0.001 | ||||
| 0 CCI | 5,200 (66.9%) | 3,841 (69.7%) | 707 (63.1%) | 652 (57.0%) | |
| 1 CCI | 1,446 (18.6%) | 974 (17.7%) | 212 (18.9%) | 260 (22.8%) | |
| 2 CCI | 661 (8.5%) | 412 (7.5%) | 124 (11.1%) | 125 (10.9%) | |
| 3+ CCI | 468 (6.0%) | 285 (5.1%) | 77 (6.9%) | 106 (9.3%) | |
| Charlson comorbidity index with revised Quan weights | < 0.001 | ||||
| 0 CCI | 5,883 (75.7%) | 4,363 (79.2%) | 784 (70.0%) | 736 (64.4%) | |
| 1 CCI | 625 (8.0%) | 416 (7.5%) | 91 (8.1%) | 118 (10.3%) | |
| 2 CCI | 882 (11.3%) | 517 (9.4%) | 175 (15.6%) | 190 (16.6%) | |
| 3+ CCI | 385 (5.0%) | 216 (3.9%) | 70 (6.3%) | 99 (8.7%) |
a
n (%); Median (interquartile range).
b
Pearson's Chi-squared test; Kruskal-Wallis rank sum test; Fisher's exact test.