Characteristics of the study sample
| Antibody negative | Antibody positive | |
| n=5850 | n=212 | |
| Pre-existing characteristics | ||
| Age, mean (SD) | 41.6 (12.0) | 38.5 (11.2) |
| Male gender (%) | 1876 (32) | 73 (34) |
| Hispanic ethnicity (%) | 1097 (19) | 62 (29) |
| Race (%) | ||
| Asian | 1809 (31) | 57 (27) |
| Black | 354 (6) | 18 (8) |
| White | 2938 (50) | 104 (49) |
| Other | 749 (13) | 33 (16) |
| Current smoker (%) | 99 (2) | 3 (1) |
| Current vape user (%) | 83 (1) | 4 (2) |
| Medical conditions (%) | ||
| Asthma | 733 (13) | 14 (7) |
| Autoimmune disease | 228 (4) | 4 (2) |
| Cancer | 195 (4) | 3 (1) |
| Cardiovascular | 127 (2) | 2 (1) |
| Chronic obstructive pulmonary disease | 84 (2) | 0 (0) |
| Diabetes mellitus | 371 (7) | 8 (4) |
| Hypertension | 967 (17) | 26 (13) |
| BMI, mean (SD) | 26.7 (5.6) | 26.3 (5.1) |
| Obesity, BMI≥30 (%) | 998 (23) | 32 (21) |
| Potential COVID-19-related exposures | ||
| Personal diagnosis of COVID-19 (%) | 530 (9) | 104 (50) |
| Household member diagnosed with COVID-19 (%) | 51 (1) | 31 (15) |
| Domestic travel since September 2019 (%) | 2127 (37) | 54 (26) |
| International travel since September 2019 (%) | 1324 (23) | 44 (21) |
| Regular contact with patients with COVID-19 (%) | 1358 (24) | 86 (41) |
| Work on a unit housing/caring for patients with COVID-19 (%) | 1600 (27) | 93 (44) |
| Type of dwelling (%) | ||
| Apartment | 2636 (46) | 93 (44) |
| House | 2914 (51) | 107 (51) |
| Other | 216 (4) | 9 (4) |
| Number of people living in the home, mean (SD) | 2.3 (1.7) | 2.4 (1.8) |
| Any persons in the home under age 18 years (%) | 1843 (32) | 65 (31) |
| Any persons in the home under age 12 years (%) | 1467 (25) | 51 (24) |
| Cats as household pets (%) | 783 (13) | 27 (13) |
| Dogs as household pets (%) | 2189 (37) | 95 (45) |
| Potential COVID-19-related responses | ||
| Fever (%) | 497 (9) | 87 (43) |
| Chills (%) | 683 (12) | 95 (46) |
| Headache (%) | 2061 (36) | 126 (61) |
| Conjunctivitis (%) | 162 (3) | 14 (7) |
| Anosmia (%) | 252 (4) | 107 (52) |
| Nasal congestion (%) | 1611 (28) | 104 (51) |
| Rhinorrhoea (%) | 1493 (26) | 82 (41) |
| Dry cough (%) | 1235 (22) | 108 (53) |
| Productive cough (%) | 542 (10) | 50 (25) |
| Sore throat (%) | 1368 (24) | 81 (40) |
| Chest pain (%) | 453 (8) | 45 (22) |
| Dyspnoea (%) | 604 (11) | 66 (33) |
| Anorexia (%) | 390 (7) | 78 (38) |
| Nausea (%) | 657 (12) | 52 (25) |
| Vomiting (%) | 188 (3) | 15 (8) |
| Diarrhoea (%) | 853 (15) | 59 (29) |
| Myalgias (%) | 1033 (18) | 117 (58) |
| Fatigue (%) | 1447 (25) | 135 (66) |
| Skin changes (%) | 261 (5) | 15 (8) |
| Stroke symptoms (%) | 35 (1) | 3 (2) |
| Sneezing (%) | 1863 (33) | 94 (47) |
BMI, body mass index.