Table 2. Cohort description, attack rates, univariable analysis, and multivariable analysis of risk factors for SARS-CoV-2 infection in outbreak in a meat processing plant, Southern Germany, April to June 2020 (n = 1,258).
| Characteristic | N total | % total | N cases | AR (%) | Univariable analysis | Multivariable analysis | ||
|---|---|---|---|---|---|---|---|---|
| RR (95% CI) | p value | aRR (95% CI) | p value | |||||
| Sex | ||||||||
| Male | 929 | 73.8 | 319 | 34.0 | Ref | Ref | ||
| Female | 329 | 26.2 | 134 | 40.4 | 1.19 (1.01–1.38) | 0.034 | 1.15 (0.98–1.34) | 0.084 |
| Age group | ||||||||
| 17–29 years | 355 | 28.2 | 139 | 38.6 | Ref | NA | ||
| 30–39 years | 285 | 22.7 | 88 | 30.6 | 0.79 (0.63–0.98) | 0.032 | NA | |
| 40–49 years | 327 | 26.0 | 124 | 37.6 | 0.97 (0.80–1.17) | 0.741 | NA | |
| 50–77 years | 189 | 23.1 | 102 | 34.9 | 0.90 (0.73–1.09) | 0.286 | NA | |
| Age in years (continuous) | 1.00 (0.99–1.00) | 0.698 | 1.01 (1–1.01) | 0.103 | ||||
| Type of contract | ||||||||
| Directly contracted | 386 | 30.7 | 84 | 21.7 | Ref | Ref | ||
| Subcontracted | 830 | 70.0 | 361 | 43.0 | 2.00 (1.64–2.47) | < 0.001 | 1.43 (1.06–1.96) | 0.023 |
| Externala | 42 | 3.3 | 8 | 18.6 | 0.88 (0.41–1.56) | 0.689 | 0.43 (0.1–1.21) | 0.162 |
| Work area | ||||||||
| Administration / office work | 84 | 6.7 | 13 | 15.3 | Ref | Ref | ||
| Meat packaging | 445 | 35.4 | 157 | 35.0 | 2.28 (1.43–4.05) | 0.002 | 1.61 (0.94–2.97) | 0.104 |
| Meat cutting | 409 | 32.5 | 210 | 50.6 | 3.32 (2.10–5.86) | < 0.001 | 2.44 (1.45–4.48) | 0.002 |
| Transport | 80 | 6.4 | 7 | 8.8 | 0.57 (0.22–1.31) | 0.197 | 0.53 (0.21–1.23) | 0.155 |
| Slaughtering | 61 | 4.8 | 26 | 42.6 | 2.75 (1.58–5.12) | < 0.001 | 2.35 (1.32–4.45) | 0.005 |
| Cleaning | 56 | 4.5 | 12 | 21.4 | 1.38 (0.67–2.84) | 0.368 | 1.76 (0.82–3.66) | 0.128 |
| Shipping | 36 | 2.9 | 7 | 19.4 | 1.26 (0.51–2.81) | 0.591 | 1.18 (0.48–2.67) | 0.695 |
| Quality assurance | 17 | 1.4 | 2 | 11.8 | 0.76 (0.13–2.44) | 0.700 | 0.71 (0.12–2.28) | 0.631 |
| Meat handling (freezer) | 14 | 1.1 | 5 | 35.7 | 2.31 (0.85–5.15) | 0.057 | 1.66 (0.6–3.86) | 0.262 |
| Veterinary/Meat inspectionb | 13 | 1.0 | 5 | 38.5 | 2.49 (0.93–5.49) | 0.036 | 4.77 (1.16–23.68) | 0.036 |
| Other | 43 | 3.4 | 9 | 20.0 | 1.35 (0.6–2.89) | 0.440 | 1.37 (0.62–2.91) | 0.412 |
| Air-conditioning source (n = 1,205) | ||||||||
| No source | 131 | 10.4 | 14 | 10.6 | Ref | NA | ||
| Source 1 | 641 | 51.0 | 285 | 44.0 | 4.16 (2.63–7.25) | < 0.001 | NA | |
| Source 2 | 252 | 20.0 | 93 | 36.6 | 3.45 (2.14–6.11) | < 0.001 | NA | |
| Source 3 | 42 | 3.3 | 7 | 16.7 | 1.56 (0.63–3.49) | 0.299 | NA | |
| Source 4 | 27 | 2.1 | 4 | 14.3 | 1.39 (0.42–3.53) | 0.535 | NA | |
| Source 5 | 68 | 5.4 | 27 | 39.7 | 3.72 (2.14–6.85) | < 0.001 | NA | |
| Multiple | 44 | 3.5 | 9 | 20.0 | 1.91 (0.85–4.06) | 0.096 | NA | |
| Housing (n employees living together) (n = 1,245) | ||||||||
| 1 | 400 | 31.8 | 106 | 26.3 | Ref | Ref | ||
| 2–4 | 145 | 11.5 | 44 | 29.7 | 1.15 (0.84–1.52) | 0.369 | 0.89 (0.66–1.19) | 0.445 |
| 5–9 | 57 | 4.5 | 29 | 50.9 | 1.92 (1.38–2.55) | < 0.001 | 1.01 (0.72–1.39) | 0.928 |
| 10 + | 644 | 51.2 | 274 | 42.2 | 1.61 (1.34–1.94) | < 0.001 | 0.93 (0.75–1.18) | 0.508 |
| Distance to workplace (n = 1,245) | ||||||||
| Less than 1 km | 98 | 7.8 | 40 | 40.8 | Ref | Ref | ||
| More than 1 km | 1147 | 91.2 | 413 | 35.7 | 0.88 (0.7–1.16) | 0.327 | 1.06 (0.83–1.41) | 0.685 |
AR: attack rate; ARR: adjusted risk ratio; CI: confidence interval; NA: not applicable; Ref: reference; SARS-CoV2: severe acute respiratory syndrome coronavirus 2.
a External employees – employees contracted by another company/organisation whose work is conducted in the plant (e.g., veterinarians, cleaning personnel, etc.
b 2 persons were meat inspection employees; 12 employees had no PCR or serology result (3 female); 10 were subcontracted; 1 directly contracted; 1 external; 6 worked in the meat cutting area; 3 worked in the packaging area; 2 worked in other areas; and 1 worked in administration; all lived more than 1 km from the plant; 5 shared accommodations with > 10 co-workers; 3 shared accommodations with 2–4 co-workers; and 1 shared accommodations with 1 co-worker.
Case definition: RT-PCR positive result for SARS-CoV-2 or presence for IgG antibody.