Trends and risk factors of SARS-CoV-2 infection in asymptomatic blood donors

Abstract

Background: A large proportion of SARS-CoV-2-infected individuals does not develop severe symptoms. Serological tests help in evaluating the spread of infection and disease immunization. The aim of this study was to prospectively examine the trends and risk factors of SARS-CoV-2 infection in blood donors. Study design and methods: We screened 8798 asymptomatic donors presenting in Milan from July 2020 to February 2021 (10,680 presentations) before the vaccination campaign for anti-nucleoprotein (NP) antibodies, and for anti-spike receptor-binding domain (RBD) antibodies and nasopharyngeal swab PCR in those who tested positive. Results: The prevalence of anti-NP+/RBD+ tests increased progressively with time up to ~15% (p 80 AU/ml). Anti-RBD titers declined during follow-up, depending on baseline titers (p