Certain professional categories are at a high occupational exposure to COVID-19. The aim of this survey was to quantify the seroprevalence of SARS-CoV-2 among police officers in Italy and identify its correlates. In this cross-sectional study, a nationally representative sample of State police employees was tested for IgG and IgM before the start of the National vaccination campaign. A total of 10,535 subjects (approximately 10% of the total workforce) participated in the study. The overall seroprevalence was 4.8% (95% CI: 4.4-5.3%). However, seropositivity was unevenly distributed across the country with a clear (p < 0.001) North-South gradient. In particular, the seroprevalence was 5.6 times higher in northern regions than in southern regions (9.0% vs. 1.6%). Most (71.2%) seropositive subjects reported having no recent symptoms potentially attributable to SARS-CoV-2 infection. Previous dysosmia, dysgeusia, and influenza-like illness symptoms were positive predictors of being seropositive. However, the prognostic value of dysosmia depended (p < 0.05) on both sex and prior influenza-like illness. The baseline seroprevalence of SARS-CoV-2 in police employees is considerable. A significant risk of occupational exposure, frequent asymptomatic cases and the progressive waning of neutralizing antibodies suggest that the police workers should be considered among the job categories prioritized for the booster COVID-19 vaccine dose.
Keywords: COVID-19; Italy; SARS-CoV-2; occupational exposure; police officers; seroprevalence.