Serum Prevalence of SARS-Cov-2 Antibodies in Pre-pandemic Blood Samples (SPARE)

The first reports of infections caused by SARS-CoV-2 were released from Wuhan, China in December 2019. From there, the infection quickly spread into a pandemic form. The clinical manifestation of the infection varies enormously, from totally asymptomatic or mildly symptomatic forms, with nonspecific and flu-like manifestations, to an acute respiratory distress syndrome which, in patients requiring hospitalization in the ICU and mechanical ventilation invasive, can lead to death, especially in elderly subjects and carriers of co-morbidities. Recently, the association of blood groups ABO as possible biological markers of susceptibility to COVID-19, has been evaluated, linking blood type O with a lower chance of infection, blood type A with the highest risk, and blood group B with the greatest complications. In Italy, the first non "imported" case dates back to February 2020, although new evidence on subjects tested positive for the antibody assay on serum samples suggests that the virus started to circulate before the official date. Few are the data relating to asymptomatic infections or with mild non-specific and nuanced symptoms that have been quantified in about 85% of the total number of infected. Moreover, thanks to the availability of serological tests that identify the presence of anti-SARS-CoV-2 antibodies, it emerged that a proportion of the population was infected by the virus and developed an antibody response and that almost 30% of the people with antibodies were asymptomatic. In order to evaluate the seroprevalence of COVID-19 infection among asymptomatic subjects the investigators will conduct specific serological tests (total antibodies) to identify the prevalence of SARS-2-CoV antibodies among healthy blood donors who went to transfusion facilities of the DIMT in Venice during the pandemic (about 2500 periodic donors who referred to the Transfusion Center in the period between May and October 2019). Patients afferent to the Interinstitutional Multidi