Demographics, comorbidities and behavioural risk factors of participants in the COVID-19 Citizen Science Study assessed at the time of enrolment, divided by participants who later tested positive for COVID-19 during the study period and participants who did not
| Participants with incident SARS-CoV-2 (n=112) | Participants without incident SARS-CoV-2 (n=28 463) | P value | |
| Age, median (IQR) | 46.0 (37.0–55.5) | 44.0 (36.0–55.0) | 0.84 |
| Age category, n (%) | 0.71 | ||
| 18–29 | 12 (10.7) | 2594 (9.2) | |
| 30–39 | 26 (23.2) | 7832 (27.7) | |
| 40–49 | 31 (27.7) | 7121 (25.2) | |
| 50–59 | 27 (24.1) | 6041 (21.3) | |
| 60+ | 16 (14.3) | 4711 (16.6) | |
| Female biological sex, n (%) | 71 (65.1) | 18 908 (67.7) | 0.79 |
| Race/ethnicity, n (%) | 0.25 | ||
| White | 94 (86.2) | 23 814 (85.2) | |
| Black | 2 (1.8) | 229 (0.8) | |
| Hispanic (any race) | 9 (8.3) | 1902 (6.8) | |
| Asian or Pacific Islander | 1 (0.9) | 1384 (5.0) | |
| Other (including multiracial) | 3 (2.8) | 618 (2.2) | |
| Highest level of education, median, n (%) | <0.001 | ||
| Less than high school | 1 (0.9) | 101 (0.4) | |
| High school graduate | 8 (7.3) | 882 (3.2) | |
| Some college | 24 (22.0) | 4091 (14.7) | |
| College graduate | 40 (36.7) | 9891 (35.4) | |
| Postgraduate | 33 (30.3) | 12 690 (45.5) | |
| Other | 3 (2.8) | 247 (0.9) | |
| MacArthur Subjective Social Status Ladder, mean (SD) | 6.6 (1.5) | 6.9 (1.6) | 0.054 |
| Working in healthcare, n (%) | 31 (27.7) | 5719 (20.1) | 0.046 |
| Medical comorbidities, n (%) | |||
| Atrial fibrillation | 2 (1.8) | 835 (3.0) | 0.47 |
| Anaemia | 8 (7.2) | 2957 (10.5) | 0.26 |
| AnaemiaAsthma | 9 (8.0) | 2815 (9.9) | 0.5 |
| Coronary artery disease | 2 (1.8) | 693 (2.4) | 0.65 |
| Cancer | 5 (4.5) | 908 (3.2) | 0.45 |
| Congestive heart failure | 1 (0.9) | 174 (0.6) | 0.71 |
| COPD | 2 (1.8) | 444 (1.6) | 0.84 |
| Diabetes | 8 (7.1) | 1163 (4.1) | 0.11 |
| Hypertension | 31 (27.7) | 5675 (20.1) | 0.045 |
| HIV | 3 (2.7) | 108 (0.4) | <0.001 |
| Other immunodeficiency | 4 (3.6) | 542 (1.9) | 0.21 |
| History of heart attack | 2 (1.8) | 283 (1.0) | 0.4 |
| Sleep apnoea | 13 (11.7) | 3019 (10.8) | 0.75 |
| History of stroke | 2 (1.8) | 355 (1.3) | 0.6 |
| Alcohol use | 0.1 | ||
| None | 26 (24.8) | 6541 (25.7) | |
| >0–7 drinks per week | 60 (57.1) | 13 362 (52.6) | |
| >7–14 drinks per week | 18 (17.1) | 3764 (14.8) | |
| >14 drinks per week | 1 (1.0) | 1743 (6.9) | |
| Smoking | |||
| Cigarette use in the last 30 days | 8 (7.2) | 1421 (5.0) | 0.29 |
| E-cigarette use in the last 30 days | 5 (4.5) | 723 (2.6) | 0.19 |
| Marijuana use in the last 30 days | 10 (9.0) | 2650 (9.5) | 0.87 |
| Sleep duration, median (IQR) | 7.0 (6.0–8.0) | 7.0 (6.0–8.0) | |
| Living with children at home, n (%) | 34 (30.4) | 8926 (31.6) | 0.78 |
| Living with pets at home, n (%) | 73 (65.8) | 18 442 (64.9) | 0.86 |
| Use of face masks, n (%) | 0.29 | ||
| ‘Never’ | 10 (9.3) | 1650 (6.0) | |
| ‘Sometimes’ | 17 (15.7) | 3359 (12.2) | |
| ‘Most times’ | 75 (69.4) | 20 591 (74.8) | |
| ‘Always’ | 6 (5.6) | 1910 (6.9) | |
| Handwashing frequency, n (%) | 0.32 | ||
| <1 time/day | 0 (0) | 55 (0.2) | |
| ~1 time/day | 1 (0.9) | 341 (1.2) | |
| 2–4 times/day | 16 (14.3) | 4699 (16.5) | |
| 5–10 times/day | 47 (42.0) | 13 866 (48.7) | |
| >10 times/day | 48 (42.9) | 9502 (33.4) | |
| Exercise frequency, n (%) | <0.001 | ||
| Never/rarely | 5 (4.5) | 1591 (5.6) | |
| <1 time/month | 16 (14.3) | 2369 (8.3) | |
| <1 time/week | 23 (20.5) | 3678 (12.9) | |
| Approximately weekly | 12 (10.7) | 3668 (12.9) | |
| 2–4 days/week | 30 (26.8) | 8956 (31.5) | |
| >4 days/week | 23 (20.5) | 8107 (28.5) | |
| Number of contacts in the past 24 hours, mean (SD) | 3.8 (6.2) | 3.1 (7.3) | 0.36 |
| Number of events with 10 or more people in the past week, mean (SD) | 3.8 (14.0) | 1.9 (9.8) | 0.035 |
| Number of gym visits in the past week, mean (SD) | 0.4 (3.4) | 0.9 (6.6) | 0.5 |
| Number of visits to movie theatres in the past week, mean (SD) | 0.1 (0.9) | 0.1 (1.6) | 0.81 |
| Number of visits to restaurants in the past week, mean (SD) | 3.4 (9.3) | 2.2 (7.7) | 0.095 |
COPD, chronic obstructive pulmonary disease.