Table 1

Association between selected variables and prevalence of positive tests (anti-SARS-CoV-2 IgG ≥15 AU/mL) among healthcare workers in a large university hospital, Milan, Italy, 27 April 2020 to 12 June 2020

VariableWorkersPositive test
NN%P value*OR†95% CI†
All40553097.6
Country of origin
 Italy38692827.3<0.0011.00Reference
 Other1862714.51.821.07 to 3.06
Gender
 Women28232077.30.301.00Reference
 Men12321028.31.130.85 to 1.52
Age (years)
 <30668649.60.021.00Reference
 30–391018787.70.740.51 to 1.07
 40–49858485.60.460.30 to 0.72
 50–591128817.20.640.43 to 0.95
 60+383389.90.830.50 to 1.36
Occupation
 Physicians, including residents1292937.20.0060.990.64 to 1.53
 Nurses, midwives1230998.01.310.85 to 2.04
 Healthcare assistants3204012.51.841.04 to 3.25
 Health technicians‡585356.00.840.50 to 1.40
 Clerical workers, technicians628426.71.00Reference
Frontline healthcare workers
 Never20611497.20.421.00Reference
 Ever17301377.90.920.69 to 1.24
 Missing264238.7
BMI
 <20684466.70.040.900.62 to 1.32
 20–24.9920351457.11.00Reference
 25–29.99945798.41.100.80 to 1.52
 30+314319.91.520.98 to 2.35
 Missing77810.4
Cigarette smoking
 Never24932108.4<0.0011.00Reference
 Former552498.91.120.79 to 1.58
 Current842344.00.410.27 to 0.61
 Missing168169.5
  • *From χ2 test. For BMI: from χ2 test for trend. Missing data not included in analyses.

  • †From a multivariable logistic regression model including country of origin, gender, age, occupation, frontline area, BMI and smoking. Missing data not included in analyses.

  • ‡Includes biologists, radiology and laboratory technicians, psychologists and other health technicians.

  • BMI, body mass index.;