Table 2.
Incidence and incidence rate ratios (IRR) of COVID-19 cases (possible, probable and confirmed), by risk contact-event with SARS-CoV-2-positive general practitioners (GP)
| Type of risk contact | Exposure | Total (n = 89) | % | No case (n = 67) | % | Case (n = 22) | % | Incidence rate ratios | 95% CI lower | 95% CI upper |
|---|---|---|---|---|---|---|---|---|---|---|
| GP | GP Y | 46 | 51.7 | 36 | 53.7 | 10 | 45.5 | 1 (ref) | (ref) | (ref) |
| GP X | 43 | 48.3 | 31 | 46.3 | 12 | 54.5 | 1.28 | 0.55 | 3.04 | |
| Phase of infection of GPs | Symptomatic | 20 | 22.5 | 16 | 23.9 | 4 | 18.2 | 1 (ref) | (ref) | (ref) |
| Pre-symptomatic | 69 | 77.5 | 51 | 76.1 | 18 | 81.8 | 1.30 | 0.49 | 4.51 | |
| Duration | ≥10 min | 70 | 78.7 | 52 | 77.6 | 18 | 81.8 | 1 (ref) | (ref) | (ref) |
| <10 min | 18 | 20.2 | 15 | 22.4 | 3 | 13.6 | 0.65 | 0.15 | 1.91 | |
| Facemask worn by GP | No facemask | 53 | 59.6 | 39 | 58.2 | 14 | 63.6 | 1 (ref) | (ref) | (ref) |
| Facemask | 31 | 34.8 | 24 | 35.8 | 7 | 31.8 | 0.85 | 0.32 | 2.05 | |
| Unknown | 5 | 5.6 | 4 | 6.0 | 1 | 4.5 | – | – | – | |
| Duration and facemask worn by GP combineda | Exposed (contact ≥10 min and/or GP not wearing facemask) | 75 | 84.3 | 53 | 79.1 | 22 | 100 | 1 (ref) | (ref) | (ref) |
| Unexposed (GP wore facemask and <10 min contact) | 14 | 15.7 | 14 | 20.9 | 0 | 0.0 | 0.21 | 0.01 | 0.99 | |
| Risk contact scoreb | Per point (continuous) | NA | NA | NA | NA | NA | NA | 1.23 | 0.76 | 2.15 |
a
IRR calculated using Haldane-Anscombe correction.
b
Risk contact score (scale 0–3), one point for each: duration (1 point if ≥10 min), distance (1 point for <1 m and/or physical examination), GP with facemask (1 point for contact without a facemask, or contact ≥10 min with a facemask).