| | Characteristic | Overall | Negative cohort | Positive cohort |
| | (a) Broad Cohort | | n | 2,404 | 2,039 | 365 | | Age at cohort entrance, n (%) | | <5 years | 127 (5.2) | 115 (5.6) | 12 (3.3) | | 5–11 years | 664 (27.6) | 591 (29.0) | 73 (20.0) | | 12–15 years | 808 (33.6) | 669 (32.8) | 139 (38.1) | | 16–20 years | 805 (33.5) | 664 (32.6) | 141 (38.6) | | Sex, n (%) | | Female | 1,224 (50.9) | 1,044 (51.2) | 180 (49.3) | | Male/other/unknown | 1,180 (49.0) | 995 (48.7) | 186 (50.7) | | Race/ethnicity, n (%) | | White non-Hispanic | 1,484 (61.7) | 1,283 (62.9) | 201 (55.1) | | Black non-Hispanic | 361 (15.0) | 286 (14.0) | 75 (20.5) | | Hispanic | 340 (14.1) | 281 (13.8) | 59 (16.2) | | Other/unknown | 219 (9.1) | 189 (9.2) | 30 (8.2) | | Insurance class, n (%) | | Public | 1,082 (45.0) | 901 (44.2) | 181 (49.6) | | Private | 775 (32.2) | 685 (33.6) | 90 (24.7) | | Other/unknown | 547 (22.8) | 453 (22.2) | 94 (25.8) | | Cohort entry perioda | | Original strain (March 2020–April 2021) | 1,429 (59.4) | 1,208 (59.2) | 221 (60.5) | | Alpha (May–July 2021) | 276 (11.5) | 258 (12.7) | 18 (4.9) | | Delta (Aug–December 2021) | 699 (29.1) | 573 (28.1) | 126 (34.5) | | Test location, n (%) | | Emergency department | 667 (27.7) | 520 (25.5) | 147 (40.3) | | Inpatient | 540 (22.5) | 486 (23.8) | 54 (4.8) | | Outpatient office | 436 (18.1) | 380 (18.6) | 56 (15.3) | | Outpatient: test only | 761 (31.7) | 653 (32.0) | 108 (29.6) |
| | (b) Narrow Cohort | | n | 1,221 | 1,028 | 193 | | Age at cohort entrance, n (%) | | <5 years | 70 (5.8) | 64 (6.2) | 6 (3.1) | | 5–11 years | 371 (30.4) | 331 (32.2) | 40 (20.7) | | 12–15 years | 434 (35.5) | 347 (33.8) | 87 (45.1) | | 16–20 years | 346 (28.3) | 286 (27.8) | 60 (31.1) | | Sex, n (%) | | Female | 605 (49.5) | 513 (49.9) | 92 (47.7) | | Male | 616 (50.5) | 515 (50.1) | 101 (52.3) | | Race/ethnicity, n (%) | | Non-Hispanic White | 774 (63.4) | 663 (64.5) | 111 (57.5) | | Non-Hispanic Black | 184 (15.1) | 146 (14.2) | 38 (19.7) | | Hispanic | 168 (13.8) | 138 (13.4) | 30 (15.5) | | Other/unknown | 95 (12.2) | 81 (7.9) | 14 (7.3) | | Insurance class, n (%) | | Public | 541 (44.3) | 449 (43.7) | 92 (47.7) | | Private | 356 (29.2) | 315 (30.6) | 41 (21.2) | | Other/unknown | 324 (26.5) | 264 (25.7) | 60 (31.1) | | Cohort entry period | | Original strain (March 2020–April 2021) | 708 (58.0) | 597 (58.1) | 111 (57.5) | | Alpha (May–July 2021) | 140 (11.5) | 133 (12.9) | 7 (3.6) | | Delta (August–December 2021) | 373 (30.5) | 298 (29.0) | 75 (38.9) | | Test location, n (%) | | Emergency department | 349 (28.6) | 277 (26.9) | 72 (37.3) | | Inpatient | 238 (19.5) | 211 (20.5) | 27 (14.0) | | Outpatient office | 232 (19.0) | 197 (19.2) | 35 (18.1) | | Outpatient: test only | 402 (32.9) | 343 (33.4) | 59 (30.6) |
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