This study aims to evaluate SARS-CoV-2 seroprevalence among health care workers (HCWs) and to assess self-reported risk factors for seropositivity. A total of 3255 HCWs were included and the overall seroprevalence was 7.8%. The likelihood of seropositivity was higher in participants reporting any COVID-19 symptoms within the last 4 months (OR 8.32, 95% CI 5.83-11.88, P < 0.001). Being a female HCW (OR 1.32, 95% CI 1.11-2.32, P < 0.01), having a cohabitant who was infected with SARS-CoV-2 (OR 2.55, 95% CI 1.78-3.66 P < 0.001) or a cohabitant who was a nursing home caregiver (OR 3.71, 95% CI 1.59-8.65, PÂ =Â 0.002) were independently associated with an increased risk of seropositivity. Working in a COVID-19 unit (OR 1.64, 95% CI 1.21-2.23, P < 0.001) and being exposed to a SARS-CoV-2 infected co-worker (OR 1.30,95% CI 0.97-1.74, PÂ =Â 0.016) resulted in higher seropositivity rate. Even if in-hospital exposure may play a significant role, increased infection risk is most likely attributable to household contact.