Non-ABO red cell antibodies and risk of COVID-19

It is not known whether non-ABO antibodies confers any protective effect against SARS-CoV-2 infection or COVID-19 severe illness, alone, or in conjunction with O blood group. This cohort study included 413,576 persons in Ontario, Canada with known ABO blood group and non-ABO antibody screen status, and who subsequently underwent SARS-CoV-2 viral RNA PCR testing between January and November 2020. The risk of SARS-CoV-2 infection or COVID-19 severe illness was not associated with the presence of non-ABO antibodies, even among persons with O blood group.