LACK OF NEUTRALIZING ACTIVITY IN NONCONVALESCENT SERA, REGARDLESS OF ABO BLOOD GROUP AND ANTI-A ISOAGGLUTININ TITER

Focosi, Daniele; Rosellini, Alfredo; Spezia, Pietro Giorgio; Macera, Lisa; Lanza, Maria; Paolicchi, Aldo; Biagini, Denise; Baj, Andreina; Pistello, Mauro; Maggi, Fabrizio

Background Several ABO blood groups have been associated with the likelihood of infection, severity, and/or outcome of COVID-19 in hospitalized cohorts, raising the hypothesis that anti-A isoagglutinins in non-A-group recipients could act as neutralizing antibodies against SARS-CoV-2. Materials and methods We run live virus neutralization tests using sera from 58 SARS-CoV-2 seronegative blood donors (27 O-group and 31 A-group) negatives for SARS-CoV-2 IgG to investigate what degree of neutralizing activity could be detected in their sera and eventual correlation with anti-A isoagglutinin titers. Results We could not find clinically relevant neutralizing activity in any blood group, regardless of anti-isoagglutinin titer, Discussion Our findings suggest that mechanisms other than neutralization explain the differences in outcomes from COVID19 seen in different ABO blood groups.