TABLE 1.
Baseline characteristics of the study population (data from the Zurich SARS-CoV-2 Cohort Study: 2020–2021, Switzerland).
| Variable | Close contact, N = 261 | Converted case, N = 65 | Case, N = 328 |
|---|---|---|---|
| Age, years* | 35 (28, 51) | 39 (29, 55) | 38 (29, 51) |
| Sex | |||
| Female | 128/261 (49.0%) | 35/65 (53.8%) | 164/328 (50.0%) |
| Male | 133/261 (51.0%) | 30/65 (46.2%) | 164/328 (50.0%) |
| Education | |||
| Up to mandatory school | 9/257 (3.5%) | 4/65 (6.2%) | 13/327 (4.0%) |
| Vocational training/specialized baccalaureate | 89/257 (34.6%) | 22/65 (33.8%) | 133/327 (40.7%) |
| Technical college or university studies | 159/257 (61.9%) | 39/65 (60%) | 181/327 (55.3%) |
| (Missing) | 4 | 0 | 1 |
| Employment status | |||
| Employed | 205/256 (80.1%) | 53/64 (82.8%) | 265/327 (81.0%) |
| Student | 33/256 (12.9%) | 6/64 (9.4%) | 27/327 (8.3%) |
| Unemployed | 18/256 (7.0%) | 5/64 (7.8%) | 35/327 (10.7%) |
| (Missing) | 5 | 1 | 1 |
| Monthly household income (Swiss Francs) | |||
| <6,000 | 87/247 (35.2%) | 21/62 (33.9%) | 111/314 (35.4%) |
| 6,000–12,000 | 101/247 (40.9%) | 32/62 (51.6%) | 120/314 (38.2%) |
| >12,000 | 59/247 (24.9%) | 9/62 (14.5%) | 83/314 (26.4%) |
| (Missing) | 14 | 3 | 14 |
| Nationality | |||
| Swiss | 220/261 (84.3%) | 60/65 (92.3%) | 260/328 (79.3%) |
| Non-Swiss | 41/261 (15.7%) | 5/65 (7.7%) | 68/328 (20.7%) |
| Chronic comorbid conditions | |||
| At least one self-reported comorbid chronic condition | 57/252 (23%) | 13/61 (21.3%) | 69/318 (21.7%) |
| No self-reported chronic comorbid conditions | 195/252 (77%) | 48/61 (78.7%) | 249/318 (78.3%) |
| (Missing) | 9 | 4 | 10 |
| Known exposure setting | |||
| Knows or has strong suspicion | 253/257 (98.4%) | 60/65 (92.3%) | 152/328 (46.3%) |
| No | 4/257 (1.6%) | 5/65 (7.7%%) | 176/328 (53.7%) |
| (Missing) | 4 | 0 | 0 |
| Exposure setting (among those with known/suspected exposure) | |||
| Household | 72/252 (28.6%) | 32/60 (53.4%) | 22/150 (14.6%) |
| Workplace | 43/252 (17.1%) | 2/60 (3.3%) | 23/150 (15.3%) |
| Private setting | 66/252 (26.2%) | 15/60 (25.0%) | 42/150 (28.0%) |
| Public space | 45/252 (17.9%) | 8/60 (13.3%) | 43/150 (28.7%) |
| School/University | 8/252 (3.2%) | 0/60 (0.0%) | 1/150 (0.7%) |
| Other | 18/252 (7.0%) | 3/60 (5.0%) | 19/150 (12.7%) |
| Healthcare facility | 0/252 (0.0%) | 0/60 (0.0%) | 0/150 (0.0%) |
| (Missing) | 9 | 5 | 178 |
| SwissCovid app use | |||
| App non-user | 73/258 (28.3%) | 22/64 (34.4%) | 125/326 (38.3%) |
| App user | 185/258 (71.7%) | 42/64 (65.6%) | 201/326 (61.7%) |
| (Missing) | 3 | 1 | 2 |
| Reasons for non-use of the app | |||
| No knowledge of the app | 1/57 (1.8%) | 2/16 (12.5%) | 5/104 (4.8%) |
| Perception of uselessness | 13/57 (22.8%) | 3/16 (18.8%) | 29/104 (27.9%) |
| Technical problems | 14/57 (24.5%) | 4/16 (25.0%) | 21/104 (20.2%) |
| Privacy and data protection | 16/57 (28.1%) | 5/16 (31.2%) | 23/104 (22.1%) |
| Other | 13/57 (22.8%) | 2/16 (12.5%) | 26/104 (25.0%) |
| (Missing) | 16 | 6 | 21 |
*
Median (IQR).