Prevalence of SARS-CoV-2 infection and associated risk factors: A testing program and nested case-control study conducted at Sapienza University of Rome between March and June 2021 oleh Valentina Baccolini, Leonardo Maria Siena, Erika Renzi, Giuseppe Migliara, Corrado Colaprico, Alessandra Romano, Azzurra Massimi, Carolina Marzuillo, Corrado De Vito, Leandro Casini, Guido Antonelli, Ombretta Turriziani, Antonio Angeloni, Fabrizio D'Alba, Paolo Villari, Antonella Polimeni, Collaborating Group, Federica Maria Di Lella, Sofia Di Virgilio, Pierluigi Donia, Emiliano Rapiti, Donatella Maria Rodio, Geltrude Taddeo