Table 1. Baseline Characteristics of Study Participants.
| Unvaccinated | Vaccinated original cohort | SMD | Propensity score–matched vaccinated cohort | SMDa | |
|---|---|---|---|---|---|
| No. of participants | 757 | 5953 | 2141 | ||
| Received 2 doses of vaccine, No. (%) | 0 | 5517 (92.7) | 1984 (92.7) | ||
| Age, mean (SD), y | 40.7 (11.7) | 44.8 (12.5) | 0.337 | 41.0 (12.0) | 0.024 |
| Age group, No. (%) | |||||
| ≤39 y | 381 (50.3) | 2278 (38.3) | 0.289 | 1094 (51.1) | 0.043 |
| 40-59 y | 321 (42.4) | 2840 (47.7) | 872 (40.7) | ||
| ≥60 y | 55 (7.3) | 835 (14.0) | 175 (8.2) | ||
| Sex, No. (%) | |||||
| Female | 585 (77.3) | 3880 (65.2) | 0.325 | 1634 (76.3) | 0.062 |
| Male | 134 (17.7) | 1869 (31.4) | 419 (19.6) | ||
| Missing data | 38 (5.0) | 204 (3.4) | 88 (4.1) | ||
| Employment sector, No. (%) | |||||
| Administration | 324 (42.8) | 2421 (40.7) | 0.473 | 850 (39.7) | 0.160 |
| Nursing | 263 (34.7) | 1438 (24.1) | 732 (34.2) | ||
| Medicine | 44 (5.8) | 1231 (20.7) | 215 (10.0) | ||
| Other health professionsb | 98 (13.0) | 721 (12.1) | 271 (12.7) | ||
| Missing data | 28 (3.7) | 142 (2.4) | 73 (3.4) | ||
| Estimated exposure level to COVID-19, No. (%) | |||||
| Low | 661 (87.3) | 5070 (85.2) | 0.064 | 1791 (83.7) | 0.106 |
| Medium | 22 (2.9) | 188 (3.2) | 72 (3.4) | ||
| High | 74 (9.8) | 695 (11.7) | 278 (13.0) | ||
| Follow-up time, median (IQR), d | 66.0 (66.0-66.0) | 63.0 (52.0-65.0) | 0.322 | 62.0 (51.0-65.0) | 0.412 |
| No. of PCR tests per person, median (IQR) | 3.0 (1.0-5.0) | 2.0 (1.0-3.0) | 0.551 | 3.0 (1.0-5.0) | 0.090 |
| Test density per 100 d of follow-up, median (IQR) | 5.88 (2.99-8.96) | 3.03 (1.56-5.97) | 0.312 | 5.26 (2.99-8.96) | 0.076 |
Abbreviations: IQR, interquartile range; PCR, polymerase chain reaction; SMD, standardized mean difference.
a
Compares the propensity score–matched adjusted vaccinated cohort (n = 2141) with the unvaccinated cohort (n = 757).
b
Included physiotherapists, speech therapists, phlebotomists, respiratory technicians, and other paramedical staff.