Association between COVID-19 seropositivity and presence of symptoms of infection and results of PCR
| Levels | HCWs in the sample | Seropositive HCWs | % positivity (95% CI) | P value* |
| Presence of symptoms compatible with COVID-19 | ||||
| Yes | 708 | 118 | 16.7 (14.0 to 19.6) | <0.001 |
| No | 1166 | 70 | 6.0 (4.7 to 7.5) | |
| All | 1874 | |||
| Result of PCR test† (for those with symptoms) (total N=708) | ||||
| Positive | 54 | 52 | 96.3 (87.3 to 99.5) | <0.001 |
| Negative | 233 | 13 | 5.6 (3.0 to 9.4) | |
| Not performed | 421 | 53 | 12.6 (9.6 to 16.1) | |
Breslow tests for homogeneity among work category do not reject homogeneity in both cases; Cochran-Mantel-Haenzel stratified by work category is consistent with Fisher’s exact test.
*Fisher’s exact test.
†Result of PCR test as reported by the participants in the questionnaire. In the hospital system, only 33 of these 54 cases were documented. In total, among the 1874 samples, only 36 patients (1.9%) were documented as PCR positive in the hospital system (the 33 mentioned before and 3 additional who reported no symptom or positive PCR test).
HCWs, healthcare workers.