Table 1.
Characteristics of the Cohorts
| Variable | Omicron (n = 4833) |
Influenza 2021/2022 (n = 1099) |
RSV 2021/2022 (n = 453) |
Influenza 2015–2019 (n = 5709) |
RSV 2015–2019 (n = 995) |
|---|---|---|---|---|---|
| Male sex | 2459 (50.9) | 474 (43.1) | 207 (45.7) | 2628 (46.0) | 420 (42.2) |
| Age, y | 70.0 [51.0, 81.0] | 56.0 [32.0, 77.0] | 72.0 [57.0, 82.0] | 68.0 [47.0, 80.0] | 76.0 [63.0, 85.0] |
| 18–44 | 960 (19.9) | 453 (41.2) | 72 (15.9) | 1300 (22.8) | 92 (9.2) |
| 45–54 | 440 (9.1) | 82 (7.5) | 33 (7.3) | 582 (10.2) | 49 (4.9) |
| 55–64 | 636 (13.2) | 105 (9.6) | 54 (11.9) | 693 (12.1) | 129 (13.0) |
| 65–74 | 767 (15.9) | 147 (13.4) | 88 (19.4) | 984 (17.2) | 194 (19.5) |
| 75 or older | 2030 (42.0) | 312 (28.4) | 206 (45.5) | 2150 (37.7) | 531 (53.4) |
| Region of birth | |||||
| Africa | 176 (3.6) | 67 (6.1) | 15 (3.3) | 240 (4.2) | 30 (3.0) |
| The Americas | 139 (2.9) | 41 (3.7) | 8 (1.8) | 152 (2.7) | 21 (2.1) |
| Asia or Oceania | 705 (14.6) | 249 (22.7) | 66 (14.6) | 866 (15.2) | 87 (8.7) |
| Europe | 651 (13.5) | 122 (11.1) | 79 (17.4) | 798 (14.0) | 132 (13.3) |
| Sweden | 3162 (65.4) | 620 (56.4) | 285 (62.9) | 3650 (63.9) | 725 (72.9) |
| Missing | 0 (0.0) | 0 (0.0) | 0 (0.0) | 3 (0.1) | 0 (0.0) |
| Education level | |||||
| Primary | 1248 (25.8) | 328 (29.8) | 119 (26.3) | 1490 (26.1) | 294 (29.5) |
| Secondary | 1876 (38.8) | 418 (38.0) | 161 (35.5) | 2299 (40.3) | 386 (38.8) |
| Tertiary | 1444 (29.9) | 293 (26.7) | 147 (32.5) | 1710 (30.0) | 271 (27.2) |
| Missing | 265 (5.5) | 60 (5.5) | 26 (5.7) | 210 (3.7) | 44 (4.4) |
| Cancer | 553 (11.4) | 84 (7.6) | 61 (13.5) | 537 (9.4) | 149 (15.0) |
| Cardiac or cerebrovascular disease | 1722 (35.6) | 286 (26.0) | 177 (39.1) | 1805 (31.6) | 467 (46.9) |
| Chronic kidney failure | 679 (14.0) | 101 (9.2) | 73 (16.1) | 450 (7.9) | 117 (11.8) |
| Chronic liver disease | 133 (2.8) | 26 (2.4) | 17 (3.8) | 137 (2.4) | 26 (2.6) |
| Chronic lung disease | 697 (14.4) | 149 (13.6) | 116 (25.6) | 893 (15.6) | 274 (27.5) |
| Diabetes | 1009 (20.9) | 167 (15.2) | 111 (24.5) | 976 (17.1) | 215 (21.6) |
| Home care services or nursing home | 1327 (27.5) | 188 (17.1) | 125 (27.6) | 1094 (19.2) | 302 (30.4) |
| Hypertension | 2336 (48.3) | 394 (35.9) | 242 (53.4) | 2349 (41.1) | 529 (53.2) |
| Immunocompromised state | 902 (18.7) | 125 (11.4) | 92 (20.3) | 882 (15.4) | 232 (23.3) |
| Neurologic conditions, including dementia | 548 (11.3) | 69 (6.3) | 40 (8.8) | 534 (9.4) | 118 (11.9) |
| Obesity | 461 (9.5) | 118 (10.7) | 56 (12.4) | 385 (6.7) | 67 (6.7) |
| COVID-19 vaccine doses | |||||
| Unvaccinated | 1068 (22.1) | 214 (19.5) | 46 (10.2) | NA | NA |
| 1 dose | 140 (2.9) | 51 (4.6) | 20 (4.4) | NA | NA |
| 2 doses | 1128 (23.3) | 507 (46.1) | 278 (61.4) | NA | NA |
| 3 doses | 1740 (36.0) | 295 (26.8) | 106 (23.4) | NA | NA |
| 4 doses | 757 (15.7) | 32 (2.9) | 3 (0.7) | NA | NA |
| Previous SARS-CoV-2 infection | 389 (8.0) | 242 (22.0) | 77 (17.0) | NA | NA |
Abbreviations: COVID-19, coronavirus disease 2019; NA, not applicable; RSV, respiratory syncytial virus; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2.