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Table 2 Risk factors for SARS-CoV-2 seroconversion

From: Healthcare institutions’ recommendation regarding the use of FFP-2 masks and SARS-CoV-2 seropositivity among healthcare workers: a multicenter longitudinal cohort study

  Baseline n = 2794 Follow up n = 2227
n total n sero-conversion % sero-conversion OR 95% CI p value n total N sero-conversion % Sero-conversion OR 95% CI p value
Age             
Per 10 years 2794 99   1.10 0.93–1.29 0.267 2227 290   0.99 0.98–1.00 0.104
Sex             
Female 2197 76 3.5     1763 227 12.9    
Male 597 23 3.9 1.12 0.68–1.77 0.645 464 63 13.6 1.06 0.78–1.43 0.689
Blood group             
0 722 25 3.5     695 74 10.6    
A 693 32 4.6 1.35 0.79–2.32 0.271 654 107 16.4 1.64 1.20–2.26 0.002
B 182 7 3.8 1.12 0.44–2.49 0.802 173 23 13.3 1.29 0.77–2.09 0.324
AB 64 0 0.0 0.00 0.00–15.72 0.977 64 14 21.9 2.35 1.20–4.35 0.009
unknown 1133 35 3.1 0.89 0.53–1.51 0.658 641 72 11.2 1.06 0.75–1.50 0.732
Employment rate             
< 60% 514 15 2.9     410 61 14.9    
60–79% 359 14 3.9 1.35 0.64–2.85 0.427 293 38 13.0 0.85 0.55–1.31 0.473
80–100% 1873 69 3.7 1.27 0.74–2.33 0.405 1436 182 12.7 0.83 0.61–1.14 0.245
Profession             
Employee without patient exposure 559 11 2.0     478 48 10.0    
Physician 376 9 2.4 1.22 0.49–2.98 0.660 273 28 10.3 1.02 0.62–1.66 0.925
Nurse 1118 51 4.6 2.38 1.28–4.85 0.010 886 143 16.1 1.72 1.23–2.46 0.002
Other employee with patient exposure 741 28 3.8 1.96 0.99–4.14 0.063 590 71 12.0 1.23 0.83–1.81 0.304
Type of patient exposure             
None 845 18 2.1     709 74 10.4    
No COVID-19 patients 1211 34 2.8 1.33 0.75–2.41 0.337 493 50 10.1 0.97 0.66–1.41 0.869
With COVID-19 patients 701 46 6.6 3.23 1.89–5.76 < 0.001 937 157 16.8 1.73 1.29–2.33 < 0.001
Unprotected exposure to COVID-19 patient             
No 664 42 6.3     880 149 16.9    
Yes 38 4 10.5 1.74 0.50–4.63 0.315 58 9 15.5 0.90 0.40–1.79 0.780
ICU employee             
No 1675 67 4.0     1219 177 14.5    
Yes 253 14 5.5 1.41 0.75–2.47 0.259 213 30 14.1 0.97 0.63–1.45 0.868
Employee at COVID-19 ward             
No 1681 52 3.1     1151 148 12.9    
Yes 246 29 11.8 4.19 2.57–6.69 < 0.001 281 59 21.0 1.80 1.28–2.51 0.001
Employee in emergency unit             
No 1531 57 3.7     1114 166 14.9    
Yes 396 24 6.1 1.67 1.00–2.69 0.041 318 41 12.9 0.85 0.58–1.21 0.37
Exposure to SARS-CoV2 infected co-worker             
No 2368 58 2.4     1665 200 12.0    
Yes 383 40 10.4 4.64 3.04–7.04 < 0.001 445 73 16.4 1.44 1.07–1.92 0.015
Non-occupational exposure to SARS-CoV2 infected person             
No or unknown 2660 83 3.1     1810 166 9.2    
Household 30 12 40.0 20.70 9.43–43.99 < 0.001 172 82 47.7 9.02 6.43–12.67 < 0.001
Outside household 61 3 4.9 1.61 0.39–4.46 0.432 157 33 21.0 2.64 1.72–3.95 < 0.001
Child (ren)living same in household             
No 2081 73 3.5     1635 209 12.8    
Yes 669 25 3.7 1.07 0.66–1.67 0.781 504 72 14.3 1.14 0.85–1.51 0.383
Regional incidence*             
Low 2393 79 3.3     1879 219 11.7    
Medium 141 1 0.7 0.16 0.01–1.94 0.151 129 23 17.8 1.68 0.78–3.61 0.184
High 260 19 7.3 1.88 0.50–7.12 0.353 219 48 21.9 2.06 1.10–3.89 0.025
FFP2 mask policy*             
Specific use 1993 68 3.4     1636 204 12.5    
General use 801 31 3.9 0.70 0.20–2.40 0.567 591 86 14.6 1.14 0.60–2.16 0.693
  1. Participants who seroconverted before the baseline assessment (n = 99) were excluded for analysis of seroconversion at follow-up. Note that total n for individual risk factors may be smaller due to missing values
  2. *For these factors determined at institutional level regression models included health care institutions as random effect