Table 1.
Demographic data for participants with COVID-19 with identified incubation period and variant
| Participants (n=20 413) | ||
|---|---|---|
| Health-care worker | 2766 (13·6%) | |
| Sex | ||
| Female | 13 760 (67·4%) | |
| Male | 6653 (32·6%) | |
| Variant | ||
| Historical | 7539 (36·9%) | |
| Alpha | 5133 (25·1%) | |
| Beta or gamma | 453 (2·2%) | |
| Delta | 4606 (22·6%) | |
| Omicron | 2682 (13·1%) | |
| Age, years | ||
| 18–29 | 4269 (20·9%) | |
| 30–39 | 5526 (27·1%) | |
| 40–49 | 4235 (20·7%) | |
| 50–59 | 3436 (16·8%) | |
| 60–69 | 2228 (10·9%) | |
| ≥70 | 719 (3·5%) | |
| Smoking status | ||
| Non-smoker, no nicotine substitution | 16 465 (80·7%) | |
| Non-smoker, nicotine substitution | 169 (0·8%) | |
| Non-smoker, electronic cigarette only | 801 (3·9%) | |
| <10 cigarettes per day | 1537 (7·5%) | |
| 10–20 cigarettes per day | 1019 (5·0%) | |
| >20 cigarettes per day | 422 (2·1%) | |
| Underlying conditions | ||
| Chronic respiratory disease | 1666 (8·2%) | |
| Hypertension | 1657 (8·1%) | |
| Underweight | 667 (3·3%) | |
| Diabetes | 459 (2·2%) | |
| Coronary artery disease | 165 (0·8%) | |
| COVID-19 vaccine status | ||
| Unvaccinated | 13 868 (67·9%) | |
| One dose, <90 days since last injection | 354 (1·7%) | |
| One dose, 90–179 days since last injection | 143 (0·7%) | |
| One dose, ≥180 days since last injection | 97 (0·5%) | |
| Two doses, <90 days since last injection | 642 (3·1%) | |
| Two doses, 90–179 days since last injection | 3266 (16·0%) | |
| Two doses, ≥180 days since last injection | 942 (4·6%) | |
| Three doses, <90 days since last injection | 903 (4·4%) | |
| Three doses, 90–179 days since last injection | 42 (0·2%) | |
| Three doses, ≥180 days since last injection | 16 (0·1%) | |
| Four doses, <90 days since last injection | 3 (<0·1%) | |
| Undated last dose of vaccine | 137 (0·7%) | |
| Previous SARS-CoV-2 infection | ||
| No | 19 744 (96·7%) | |
| Yes, virologically or serologically confirmed | 512 (2·5%) | |
| Yes, diagnosed on clinical evaluation only | 157 (0·8%) | |
| Symptoms in index case | 6819 (33·4%) | |
| Positive test for index case | 18 005 (88·2%) | |
| Mask wearing | ||
| Neither participant or index case | 15 911 (77·9%) | |
| Index case only | 495 (2·4%) | |
| Participant only | 1694 (8·3%) | |
| Both participant and index case | 2313 (11·3%) | |
| Setting of transmission | ||
| Indoors with closed windows | 15 117 (74·1%) | |
| Indoors with open windows | 4036 (19·8%) | |
| Outdoors | 1260 (6·2%) | |
Data are n (%). COVID-19 cases included in the ComCor case-control study between October, 2020, and February, 2022.