Table 1.
Characteristics of persons testing negative for SARS-CoV-2, testing positive for Delta SARS-CoV-2 (S-gene target detected, cohort Delta-Omicron BA.1), Omicron BA.1 (S-gene target not detected), and BA.2 SARS-CoV-2 (S-gene target detected, cohort Omicron BA.1-BA.2), the Netherlands, 22 November 2021 – 7 January 2022 (Cohort Delta-Omicron BA.1, n = 354,653) and 26 January − 31 March 2022 (Cohort Omicron BA.1-BA.2, n = 317,110).
| Cohort Delta-Omicron BA.1 | Cohort Omicron BA.1-BA.2 | ||||||
|---|---|---|---|---|---|---|---|
| Negative, n (%) | Delta, n (%) | Omicron BA.1, n (%) | Negative, n (%) | Omicron BA.1, n (%) | Omicron BA.2, n (%) | ||
| Total | 300,849 | 39,889 | 13,915 | 207,553 | 67,887 | 41,670 | |
| Age (years) | <=11 | 58,114 (19.3) | 9162 (23.0) | 891 (6.4) | 23,728 (11.4) | 7550 (11.1) | 3211 (7.7) |
| 12-17 | 24,497 (8.1) | 2290 (5.7) | 792 (5.7) | 13,555 (6.5) | 6567 (9.7) | 1846 (4.4) | |
| 18-29 | 54,280 (18.0) | 5399 (13.5) | 5242 (37.7) | 42840 (20.6) | 14,518 (21.4) | 9145 (21.9) | |
| 30-59 | 125,575 (41.7) | 16,862 (42.3) | 5843 (42.0) | 100,797 (48.6) | 33,469 (49.3) | 20,464 (49.1) | |
| 60+ | 38,383 (12.8) | 6176 (15.5) | 1147 (8.2) | 26,633 (12.8) | 5783 (8.5) | 7004 (16.8) | |
| Sex | Male | 140,874 (46.8) | 19,879 (49.8) | 6614 (47.5) | 92,192 (44.4) | 31,202 (46.0) | 19,009 (45.6) |
| Female | 159,975 (53.2) | 20,010 (50.2) | 7301 (52.5) | 115,361 (55.6) | 36,685 (54.0) | 22,661 (54.4) | |
| Vaccination and previous infection status | Naive | 90,945 (30.2) | 21,042 (52.8) | 3440 (24.7) | 42,182 (20.3) | 24,205 (35.7) | 10,437 (25.0) |
| Previous infection, unvaccinated | 12,691 (4.2) | 638 (1.6) | 739 (5.3) | 17,317 (8.3) | 5498 (8.1) | 2898 (7.0) | |
| Primary vaccination | 173,095 (57.5) | 17,777 (44.6) | 8134 (58.5) | 32,577 (15.7) | 14,930 (22.0) | 6871 (16.5) | |
| Booster | 12,792 (4.3) | 215 (0.5) | 1004 (7.2) | 95,872 (46.2) | 20,777 (30.6) | 19,499 (46.8) | |
| First start primary vaccination, then infection | 3406 (1.1) | 76 (0.2) | 240 (1.7) | 7020 (3.4) | 691 (1.0) | 539 (1.3) | |
| First infection, then primary vaccination | 7002 (2.3) | 139 (0.3) | 293 (2.1) | 2688 (1.3) | 597 (0.9) | 315 (0.8) | |
| Previous infection, booster | 918 (0.3) | 2 (0.0) | 65 (0.5) | 9897 (4.8) | 1189 (1.8) | 1111 (2.7) | |
| Vaccine | Comirnaty | 147,480 (49.0) | 13,504 (33.9) | 6986 (50.2) | 98,728 (47.6) | 27,008 (39.8) | 18,250 (43.8) |
| Spikevax | 21,899 (7.3) | 1262 (3.2) | 1189 (8.5) | 38,660 (18.6) | 8160 (12.0) | 7778 (18.7) | |
| Vaxzevria | 14,535 (4.8) | 2018 (5.1) | 436 (3.1) | 2422 (1.2) | 644 (0.9) | 491 (1.2) | |
| Janssen | 12,807 (4.3) | 1412 (3.5) | 1087 (7.8) | 3915 (1.9) | 1508 (2.2) | 774 (1.9) | |
| None | 103,636 (34.4) | 21,680 (54.4) | 4179 (30.0) | 59,499 (28.7) | 29,703 (43.8) | 13,335 (32.0) | |
| Unknown | 492 (0.2) | 13 (0.0) | 38 (0.3) | 4329 (2.1) | 864 (1.3) | 1042 (2.5) | |
| Median interval (IQR) vaccination or previous infection sample date and current sample date (days) | Primary vaccination | 148 (124–175) | 156 (132–184) | 159 (143–184) | 189 (162–217) | 183 (159–206) | 205 (173–231) |
| Booster | 15 (12–22) | 14 (10–19) | 15 (11–23) | 45 (31–63) | 38 (28–53) | 64 (48–78) | |
| Previous infection | 258 (184–352) | 328 (238–387) | 283 (177–388) | 236 (104–384) | 293 (148–412) | 258 (118–411) | |
| Symptoms at time of test request | Symptoms reported | 199,026 (66.2) | 27,906 (70.0) | 10,429 (74.9) | 155,486 (74.9) | 56,976 (83.9) | 37,657 (90.4) |
| No symptoms reported | 100,150 (33.3) | 11,719 (29.4) | 3418 (24.6) | 51,144 (24.6) | 10,619 (15.6) | 3873 (9.3) | |
| Unknown | 1673 (0.6) | 264 (0.7) | 68 (0.5) | 923 (0.4) | 292 (0.4) | 140 (0.3) | |