COVID-19(19) positive(16) healthcare worker(16) SARS-CoV-2(16) HCW(16) HCWs(16) Infection(13) Italy(13) antibody(11) age(11) RT-PCR(10) Surveillance(10) individual(10) healthcare(10) identify(9) diagnostic(9) reported(9) Italian(9) IgG(8) Sensitivity and specificity(8) was performed(8) vaccination(8) pandemic(8) COVID-19 infection(8) Healthcare workers(8) Health(8) sensitivity(6) determinants(6) Sociodemographic characteristics(6) SARS-COV-2 infection(6)