Table 1.
Characteristics of Healthcare Workers
| Characteristic | Overall, No. (%)a (N = 2435) | Baseline prevalent COVID-19 cases, No. (%)a (n = 21) | Incident Cohort | ||
|---|---|---|---|---|---|
| Negative, No. (%)a (n = 2344) | Incident COVID-19 cases, No. (%)a (n = 70) | SMDb | |||
| Follow-up time, person-years | 779 | 0 | 750 | 17.5 | 0.60 |
| Age, mean (SD), y | 40.4 (10.1) |
42.7(13.0) | 40.4 (10.05) |
40.6 (11.73) |
0.02 |
| Health system | |||||
| SHC | 891 (36.6) | 5 (23.8) | 855 (36.5) | 31 (44.3) | 0.16 |
| UCSF Health | 826 (33.9) | 7 (33.3) | 798 (34.0) | 21 (30.0) | |
| ZSFGH | 718 (29.5) | 9 (42.9) | 691 (29.5) | 18 (25.7) | |
| Female sex | 1923 (79.0) | 13 (61.9) | 1855 (79.1) | 55 (78.6) | 0.11 |
| Latinx ethnicity | |||||
| No | 2036 (87.8) | 17 (100.0) | 1960 (87.7) | 7 (10.6) | 0.12 |
| Yes | 267 (11.5) | 0 (0.0) | 260 (11.6) | 7 (10.6) | |
| Decline to answer | 15 (0.6) | 0 (0.0) | 15 (0.7) | 0 (0.0) | |
| Race | |||||
| White | 1411 (60.9) | 9 (52.9) | 1364 (61.1) | 38 (57.6) | 0.14 |
| Asian | 530 (22.9) | 3 (17.6) | 511 (22.9) | 16 (24.2) | |
| Black | 37 (1.6) | 1 (5.9) | 34 (1.5) | 2 (3.0) | |
| Multiracial | 137 (5.9) | 3 (17.6) | 131 (5.9) | 3 (4.5) | |
| Other | 143 (6.2) | 0 (0.0) | 138 (6.2) | 5 (7.6) | |
| Decline to answer | 58 (2.5) | 1 (5.9) | 55 (2.5) | 2 (3.0) | |
| Highest educational level | |||||
| Less than college | 33 (1.4) | 0 (0.0) | 33 (1.5) | 0 (0.0) | 0.29 |
| College | 1006 (43.4) | 6 (35.3) | 967 (43.3) | 33 (50.0) | |
| Higher than college | 1264 (54.5) | 11 (64.7) | 1222 (54.7) | 31 (47.0) | |
| Other | 15 (0.6) | 0 (0.0) | 13 (0.6) | 2 (3.0) | |
| Comorbid conditions | |||||
| None reported | 1642 (71.5) | 12 (70.6) | 1582 (71.5) | 48 (72.7) | 0.03 |
| Asthma or COPD | 328 (14.3) | 3 (17.6) | 314 (14.2) | 11 (16.7) | 0.07 |
| Diabetes mellitus, heart disease, high blood pressure, or severe obesity | 266 (11.6) | 2 (11.8) | 258 (11.7) | 6 (9.1) | 0.08 |
| Kidney disease on dialysis, liver disease, cancer, autoimmune disorder, or neurological disease |
161 (7.0) | 1 (5.9) | 154 (7.0) | 6 (9.1) | 0.08 |
| Job role | |||||
| Registered nurse or nurse manager | 1077 (44.2) | 8 (38.1) | 1035 (44.2) | 34 (48.6) | ~ |
| Clinician (MD, MD-equivalent, APP, or trainee) | 804 (33.0) | 8 (38.1) | 780 (33.3) | 16 (22.9) | |
| Research/administrative | 115 (4.7) | 1 (4.8) | 113 (4.8) | 1 (1.4) | |
| Support service | 112 (4.6) | 0 (0.0) | 110 (4.7) | 2 (2.9) | |
| Assistant or phlebotomist | 84 (3.4) | 1 (4.8) | 80 (3.4) | 3 (4.3) | |
| Laboratory or pharmacist | 77 (3.2) | 1 (4.8) | 73 (3.1) | 3 (4.3) | |
| Care coordination | 71 (2.9) | 0 (0.0) | 65 (2.8) | 6 (8.6) | |
| Clinic manager or ward clerk | 45 (1.8) | 2 (9.5) | 42 (1.8) | 1 (1.4) | |
| Respiratory or speech therapist | 33 (1.4) | 0 (0.0) | 31 (1.3) | 2 (2.9) | |
| Environmental/food services | 17 (0.7) | 0 (0.0) | 15 (0.6) | 2 (2.9) | |
| Work duties | |||||
| Direct patient care involved in intubating or suctioning patient airways | 701 (30.2) | 6 (35.3) | 670 (30.0) | 25 (37.9) | 0.30 |
| Direct patient care but not performing any airway procedures | 1220 (52.6) | 10 (58.8) | 1178 (52.7) | 32 (48.5) | |
| Staff with indirect patient contact (eg, reception, environmental services) | 128 (5.5) | 0 (0.0) | 127 (5.7) | 1 (1.5) | |
| Laboratory | 58 (2.5) | 0 (0.0) | 55 (2.5) | 3 (4.5) | |
| Work in healthcare but not with patients or biological samples | 81 (3.5) | 1 (5.9) | 78 (3.5) | 2 (3.0) | |
| Other | 131 (5.6) | 0 (0.0) | 128 (5.7) | 3 (4.5) | |
| Performed AGPc | 385 (16.0) | 3 (18.8) | 368 (15.9) | 14 (20.0) | 0.11 |
| COVID-19 exposure at work | |||||
| No exposure | 942 (38.9) | 8 (47.1) | 908 (38.9) | 26 (37.1) | 0.28 |
| Low-risk exposured | 680 (28.1) | 6 (35.3) | 661 (28.3) | 13 (18.6) | |
| High-risk exposured | 797 (32.9) | 3 (17.6) | 763 (32.7) | 31 (44.3) | |
| Time spent in the healthcare workplace | |||||
| 0 h/wk | 28 (1.2) | 0 (0.0) | 28 (1.2) | 0 (0.0) | 0.26 |
| <10 h/wk | 90 (3.7) | 2 (11.8) | 85 (3.6) | 3 (4.3) | |
| 10–20 h/wk | 169 (7.0) | 1 (5.9) | 165 (7.1) | 3 (4.3) | |
| 21–30 h/wk | 296 (12.2) | 0 (0.0) | 287 (12.3) | 9 (12.9) | |
| 31–40 h/wk | 1148 (47.5) | 5 (29.4) | 1104 (47.3) | 39 (55.7) | |
| >40 h/wk | 688 (28.4) | 9 (52.9) | 663 (28.4) | 16 (22.9) | |
| Time spent providing direct patient-facing care | |||||
| 0 h/wk | 234 (9.7) | 1 (5.9) | 226 (9.7) | 7 (10.0) | 0.38 |
| <10 h/wk | 305 (12.6) | 3 (17.6) | 299 (12.8) | 3 (4.3) | |
| 10–20 h/wk | 400 (16.5) | 4 (23.5) | 386 (16.6) | 10 (14.3) | |
| 21–30 h/wk | 397 (16.4) | 0 (0.0) | 381 (16.3) | 16 (22.9) | |
| 31–40 h/wk | 825 (34.1) | 5 (29.4) | 791 (33.9) | 29 (41.4) | |
| >40 h/wk | 258 (10.7) | 4 (23.5) | 249 (10.7) | 5 (7.1) | |
| No. in household, mean (SD) | 2.3 (17.2) | 1.5 (1.1) | 2.3 (1.7) | 2.3 (1.9) | 0.02 |
| Any children aged <18 y in household | 841 (36.5) | 2 (11.8) | 817 (36.8) | 22 (33.8) | 0.06 |
| Any adults aged ≥65 y in household | 256 (11.1) | 1 (5.9) | 245 (11.0) | 10 (15.4) | 0.13 |
| Extent of avoiding contact with people who live outside your home | |||||
| All of the time | 80 (3.3) | 2 (11.8) | 72 (3.1) | 6 (8.6) | 0.34 |
| Most of the time; I only leave my home to buy food or other essentials or to walk/exercise | 1232 (50.9) | 8 (47.1) | 1197 (51.3) | 27 (38.6) | |
| Some of the time; I have reduced the amount of time I am in public spaces, social gatherings, or at work | 1096 (45.3) | 7 (41.2) | 1052 (45.1) | 37 (52.9) | |
| None of the time | 11 (0.5) | 0 (0.0) | 11 (0.5) | 0 (0.0) | |
| Frequency of mask wearing when leaving home | |||||
| All of the time | 1778 (73.5) | 10 (58.8) | 1719 (73.7) | 49 (70.0) | 0.25 |
| Most of the time | 621 (25.7) | 7 (41.2) | 596 (25.6) | 18 (25.7) | |
| Some of the time | 17 (0.7) | 0 (0.0) | 14 (0.6) | 3 (4.3) | |
| Never | 3 (0.1) | 0 (0.0) | 3 (0.1) | 0 (0.0) | |
| Had community exposure with a person who tested positive for COVID-19 | 176 (7.3) | 1 (5.9) | 158 (6.8) | 17 (24.3) | 0.50 |
| Spent time in another country/state | 825 (34.1) | 3 (17.6) | 798 (34.2) | 24 (34.3) | <0.01 |
Abbreviations: AGPs, aerosol-generating procedures; APP, advanced practice providers; COPD, chronic obstructive pulmonary disease; COVID-10, coronavirus disease 2019; MD, medical doctor; SD, standard deviation; SHC, Stanford Health Care; SMD, standardized mean difference; UCSF, University of California, San Francisco; ZSFGH, Zuckerberg San Francisco General Hospital.
Data represent no. (%) of healthcare workers, unless otherwise stated.
The SMD is a comparative measure of effect size between groups. The magnitude of effect is considered small if the SMD is 0.2, medium at 0.5, and large at 0.8.
AGPs include intubation, extubation, chest physiotherapy, noninvasive ventilation, open suction, nebulized medications, manual ventilation, bronchoscopy, pulmonary function tests, high-frequency ventilation, laryngoscopy, autopsy, cardiopulmonary resuscitation, tracheostomy, and high-flow nasal cannula use.
Low-risk exposure at work included interacting with a patient who had COVID-19, with no reported breach in personal protective equipment (PPE) or other safety protocols. High-risk exposure included ever interacting with a patient who had COVID-19, without wearing full PPE or with a breach in any safety protocol.