Table 1:
SARS-CoV-2 antibody seroprevalence by participant characteristics
| Characteristic | Category | No. (%) of participants n = 2056 |
No. (%) of participants with positive serology n = 241 |
Seroprevalence, % | p value |
|---|---|---|---|---|---|
| Regional incidence of COVID-19* | High | 1630 (79.3) | 228 (94.6) | 14.0 | < 0.001 |
| Low | 426 (20.7) | 13 (5.4) | 3.1 | ||
| Work in a hospital where outbreaks occurred† | Yes | 789 (38.4) | 179 (74.3) | 22.7 | < 0.001 |
| No | 1267 (61.6) | 62 (25.7) | 4.9 | ||
| Recruitment unit | Emergency department | 600 (29.2) | 47 (19.5) | 7.8 | < 0.001 |
| Intensive care unit | 470 (22.9) | 29 (12.0) | 6.2 | ||
| COVID-19 unit | 496 (24.1) | 99 (41.1) | 20.0 | ||
| Non–COVID-19 unit | 490 (23.8) | 66 (27.4) | 13.5 | ||
| Main work unit | Emergency department | 580 (28.2) | 46 (19.1) | 7.9 | < 0.001 |
| Intensive care unit | 469 (22.8) | 29 (12.0) | 6.2 | ||
| COVID-19 unit | 436 (21.2) | 101 (42.0) | 23.2 | ||
| Non–COVID-19 unit | 438 (21.3) | 51 (21.2) | 11.6 | ||
| Other‡ | 133 (6.5) | 14 (5.8) | 10.5 | ||
| Age group, yr | 18–29 | 427 (20.8) | 41 (17.0) | 9.6 | 0.6 |
| 30–39 | 643 (31.3) | 78 (32.4) | 12.1 | ||
| 40–49 | 547 (26.6) | 70 (29.0) | 12.8 | ||
| 50–59 | 356 (17.3) | 43 (17.8) | 12.1 | ||
| ≥ 60 | 83 (4.0) | 9 (3.7) | 10.8 | ||
| Occupation | Physician | 432 (21.0) | 31 (12.9) | 7.2 | 0.007 |
| Nurse | 1189 (57.8) | 141 (58.5) | 11.9 | ||
| Nursing assistant | 132 (6.4) | 22 (9.1) | 16.7 | ||
| Orderly | 201 (9.8) | 36 (14.9) | 17.9 | ||
| Cleaning staff | 102 (5.0) | 11 (4.6) | 10.8 | ||
| Sex | Male | 489 (23.8) | 51 (21.2) | 10.4 | 0.3 |
| Female | 1564 (76.1) | 189 (78.4) | 12.1 | ||
| Missing§ | 3 (0.1) | – | – | ||
| Born in Canada | Yes | 1548 (75.3) | 154 (63.9) | 9.9 | < 0.001 |
| No | 503 (24.5) | 86 (35.7) | 17.1 | ||
| Missing | 5 (0.2) | – | – | ||
| Ethnicity | White | 1594 (77.5) | 163 (67.6) | 10.2 | < 0.001 |
| Black | 140 (6.8) | 31 (12.9) | 22.1 | ||
| Hispanic | 52 (2.5) | 14 (5.8) | 26.9 | ||
| Other¶ | 270 (13.1) | 33 (13.7) | 12.2 | ||
| Household | 1 adult, no child | 328 (16.0) | 31 (12.9) | 9.5 | 0.009 |
| 2 adults, no child | 480 (23.3) | 54 (22.4) | 11.3 | ||
| ≥ 3 adults, no child | 234 (11.4) | 35 (14.5) | 15.0 | ||
| 1 adult, ≥ 1 children | 155 (7.5) | 27 (11.2) | 17.4 | ||
| 2 adults, ≥ 1 children | 672 (32.7) | 64 (26.6) | 9.5 | ||
| ≥3 adults, ≥ 1 children | 187 (9.1) | 30 (12.4) | 16.0 | ||
| PCR test for SARS-CoV-2 | Yes, positive result | 193 (9.4) | 171 (71.0) | 88.6 | < 0.001 |
| Yes, negative result | 929 (45.2) | 50 (20.7) | 5.4 | ||
| No | 932 (45.3) | 20 (8.3) | 2.1 | ||
| Missing§ | 2 (0.1) | – | – | ||
| COVID-19-congruent symptoms** | Yes | 768 (37.4) | 186 (77.2) | 24.2 | < 0.001 |
| No | 1242 (60.4) | 53 (22.0) | 4.3 | ||
| Missing§ | 46 (2.2) | – | – | ||
| Chronic disease | Yes | 286 (13.9) | 37 (15.4) | 12.9 | 0.5 |
| No | 1755 (85.4) | 202 (83.8) | 11.5 | ||
| Missing§ | 15 (0.7) | – | – | ||
| Experience in the hospital | Less than 1 year | 179 (8.7) | 19 (7.9) | 10.6 | 0.4 |
| 1 to 4 year | 526 (25.6) | 70 (29.0) | 13.3 | ||
| ≥ 5 year | 1346 (65.5) | 151 (62.7) | 11.2 | ||
| Missing§ | 5 (0.2) | – | – | ||
| Primary work shift | Day | 1330 (64.7) | 159 (66.0) | 12.0 | 0.3 |
| Evening | 417 (20.3) | 54 (22.4) | 12.9 | ||
| Night | 289 (14.1) | 27 (11.2) | 9.3 | ||
| Missing§ | 20 (1.0) | – | – | ||
| Mean weekly number of workdays | ≤ 2 | 87 (4.2) | 5 (2.1) | 5.7 | 0.09 |
| ≥ 3 | 1958 (95.2) | 235 (97.5) | 12.0 | ||
| Missing§ | 11 (0.5) | – | – | ||
| Mean weekly number of workdays in a hot zone†† | ≤ 2 | 743 (36.1) | 60 (24.9) | 8.1 | < 0.001 |
| ≥ 3 | 1233 (60.0) | 173 (71.8) | 14.0 | ||
| Missing§ | 80 (3.9) | – | – | ||
| Work at another site | Yes, including long-term care | 100 (4.9) | 16 (6.6) | 16.0 | 0.3 |
| Yes, no long-term care | 194 (9.4) | 19 (7.9) | 9.8 | ||
| No | 1757 (85.5) | 204 (84.6) | 11.6 | ||
| Missing§ | 5 (0.2) | – | – | ||
| Worked in a unit affected by a COVID-19 outbreak | Never | 742 (36.1) | 36 (14.9) | 4.9 | < 0.001 |
| Rarely | 223 (10.8) | 29 (12.0) | 13.0 | ||
| Sometimes | 281 (13.7) | 39 (16.2) | 13.9 | ||
| Regularly | 561 (27.3) | 114 (47.3) | 20.3 | ||
| Do not know | 245 (11.9) | 22 (9.1) | 10.0 | ||
| Missing§ | 4 (0.2) | – | – | ||
| Removal from work because of a close contact with a COVID-19 case | Yes, family contact | 44 (2.1) | 12 (5.0) | 27.3 | < 0.001 |
| Yes, work contact‡‡ | 212 (10.3) | 81 (33.6) | 38.2 | ||
| Yes, other contact | 29 (1.4) | 3 (1.2) | 10.3 | ||
| No | 1751 (85.2) | 138 (57.3) | 7.9 | ||
| Missing§ | 20 (1.0) | – | – |
Note: PCR = polymerase chain reaction.
Incidence of COVID-19 in the region where the hospital is located (high = Montréal region; low = Capitale-Nationale and Eastern Townships regions).
Hospitals where an outbreak (involving ≥ 5 health care workers) occurred in 1 or more units targeted for recruitment.
Participant works in other type of units or in different units (e.g., roving team).
Missing = Do not know, prefer not to answer or missing value.
Includes Asian (n = 114, seroprevalence 12.3%), Middle Eastern (n = 53, seroprevalence 13.2%), other category (n = 34, seroprevalence 14.7%), answered more than 1 category (n = 46, seroprevalence 8.7%), prefer not to answer/do not know (n = 23, seroprevalence 21.7%). Fewer than 1% of participants (n = 4) preferred not to answer.
Occurrence of any symptom congruent with COVID-19 since Mar. 1, 2020 (i.e., fever, generalized malaise, extreme fatigue, cough, breathing difficulties, sore throat, loss of smell, loss of taste or diarrhea).
Zone where patients are positive for SARS-CoV-2.
Contact with a patient or another health care worker.