Characteristics of healthcare workers exposed to COVID-19, by case status
| Total N=2884 | Controls n=2316 | Cases n=568 | P value | |
| Gender, n (%) | 0.63 | |||
| Female | 794 (27.5) | 640 (27.6) | 154 (27.1) | |
| Male | 2066 (71.6) | 1656 (71.5) | 410 (72.2) | |
| Other | 2 (0.1) | 1 (<1) | 1 (0.2) | |
| Prefer not to say | 22 (0.8) | 19 (0.8) | 3 (0.5) | |
| Age, years, mean (SD) | 48 (10) | 48 (10) | 47 (10) | 0.11 |
| Country, n (%) | <0.001 | |||
| USA | 1061 (36.8) | 901 (38.9) | 160 (28.2) | |
| UK | 327 (11.3) | 233 (10.1) | 94 (16.5) | |
| Spain | 528 (18.3) | 382 (16.5) | 146 (25.7) | |
| Italy | 433 (15.0) | 359 (15.5) | 74 (13.0) | |
| Germany | 279 (9.7) | 233 (10.1) | 46 (8.1) | |
| France | 256 (8.9) | 208 (9.0) | 48 (8.5) | |
| Race/ethnicity, n (%) | 0.49 | |||
| White | 2218 (77) | 1792 (77.4) | 426 (75.0) | |
| Any mixed/multiple ethnic background | 162 (6) | 121 (5.2) | 41 (7.2) | |
| Asian | 336 (12) | 271 (11.7) | 65 (11.4) | |
| African | 48 (2) | 36 (1.6) | 12 (2.1) | |
| Other | 36 (1) | 29 (1.3) | 7 (1.2) | |
| Prefer not to say | 84 (3) | 67 (2.9) | 17 (3.0) | |
| Job classification, n (%) | 0.048 | |||
| Physician | 2723 (94.8) | 2187 (94.4) | 548 (96.5) | |
| Nurse/nurse practitioner/physician assistant | 149 (5.2) | 129 (5.6) | 20 (3.5) | |
| Physician specialty, n (%) | <0.001 | |||
| Other | 12 (0.4) | 10 (0.4) | 2 (0.4) | |
| Allergy and immunology | 29 (1.0) | 25 (1.1) | 4 (0.7) | |
| Cardiology | 281 (9.7) | 227 (9.8) | 54 (9.5) | |
| Critical care | 282 (9.8) | 230 (9.9) | 52 (9.2) | |
| Emergency medicine | 603 (20.9) | 512 (22.1) | 91 (16.0) | |
| Endocrinology, diabetes and metabolism | 98 (3.4) | 74 (3.2) | 24 (4.2) | |
| Gastroenterology | 94 (3.3) | 77 (3.3) | 17 (3.0) | |
| Haematology | 112 (3.9) | 85 (3.7) | 27 (4.8) | |
| Infectious disease | 100 (3.5) | 82 (3.5) | 18 (3.2) | |
| Internal medicine | 433 (15.0) | 322 (13.9) | 111 (19.5) | |
| Nephrology | 53 (1.8) | 38 (1.6) | 15 (2.6) | |
| Neurology | 107 (3.7) | 82 (3.5) | 25 (4.4) | |
| Pulmonology | 430 (14.9) | 354 (15.3) | 76 (13.4) | |
| Rheumatology | 101 (3.5) | 69 (3.0) | 32 (5.6) | |
| Nurse/Nurse Practitioner/Physician Assistant practice setting, n (%) | 0.36 | |||
| Emergency room | 24 (16.1) | 22 (17.1) | 2 (10.0) | |
| Intensive care unit | 50 (33.6) | 45 (34.9) | 5 (25.0) | |
| Other hospital-based department | 75 (50.3) | 62 (48.1) | 13 (65.0) | |
| Presence of pre-existing medical conditions* | 1264 (44) | 1002 (43.3) | 262 (46.1) | 0.22 |
| COVID-19 test (PCR or antibody), n (%) | <0.001 | |||
| No—I did not get a test | 748 (25.9) | 695 (30.0) | 53 (9.3) | |
| No—I did not have access to the test | 101 (3.5) | 69 (2.9) | 32 (5.6) | |
| Yes—I tested negative | 1737 (60.2) | 1552 (67.0) | 185 (32.6) | |
| Yes—I tested positive | 298 (10.3) | 0 (0) | 298 (52.5) | |
| Sleep and burnout from work, mean (SD) | ||||
| Number of sleeping hours at night | 6.7 (1.1) | 6.7 (1.1) | 6.6 (1.1) | 0.001 |
| Number of daytime napping hours | 0.9 (1.9) | 0.8 (1.8) | 1.0 (2.1) | 0.082 |
| Sleep disturbance, n (%) | ||||
| Difficulty sleeping at night | 632 (21.9) | 495 (21.4) | 137 (24.1) | 0.16 |
| Often wake up at early hours and unable to get back to sleep | 756 (26.2) | 607 (26.2) | 149 (26.2) | 0.99 |
| Sleeping pill use >3 times/week | 170 (5.9) | 130 (5.6) | 40 (7.0) | 0.19 |
| Sleep disturbance score, n (%) | 0.017 | |||
| Self-report of having one sleep problem† | 513 (17.8) | 429 (18.5) | 84 (14.8) | |
| Self-report of having two sleep problems‡ | 383 (13.3) | 304 (13.1) | 79 (13.9) | |
| Self-report of having three sleep problems§ | 93 (3.2) | 65 (2.8) | 28 (4.9) | |
| Frequency of self-reported burnout, n (%) | 0.004 | |||
| Never | 500 (17.3) | 422 (18.2) | 78 (13.7) | |
| <1 or few times a month (rarely) | 1815 (19.3) | 1444 (62.4) | 371 (65.4) | |
| 1 to few times a week (weekly) | 467 (16.2) | 379 (16.3) | 88 (15.5) | |
| Every day | 102 (3.5) | 71 (3.1) | 31 (5.5) |
Values are n (%) for categorical variables and mean (SD) for continuous variables.
Cases are defined as individuals with self-reported COVID-19-like illness (fever, cough, fatigue, loss of taste or smell) or a positive PCR or antibody test.
*Pre-existing medical condition included pre-diabetes, diabetes, high cholesterol, hypertension, cancer, coronary disease or heart attack, heart failure, prior lung disease, prior lung infection, asthma, overweight or autoimmune disease.
†Sleep disturbance was defined as ‘yes’ response to any of the following questions: (1) Do you have difficulties falling asleep at night prior to the COVID-19 pandemic? (2) Do you often wake up in the early hours, unable to get back to sleep prior to the COVID-19 pandemic? (3) Do you take sleeping pills more than three times per week prior to the COVID-19 pandemic?
‡Having two sleep problems was defined as saying yes to two of the three questions.
§Having three sleep problems was defined as saying yes to all of the questions.