Introduction:

Whether there is an influence of the ABO blood system on susceptibility to the disease and its severity is unknown.

Objective:

To analyze if there is an association between the ABO blood system phenotypes and susceptibility to SARS-CoV-2 infection and its severity.

Material and methods:

The frequency of ABO antigens was compared in 73 confirmed cases of SARS-CoV-2 infection and 52 clinically healthy donors. The severity of the infection was evaluated by comparing the frequency of antigens by severity of the disease and mortality.

Results:

The risk of SARS-CoV-2 infection is increased in subjects with antigen A vs non-A subjects (OR=1.45; 95 %: 1.061-1.921). Blood phenotype O decreases the risk of SARS-CoV-2 infection (OR= 0.686; 95 % CI: 0.522-0.903). No differences were found regarding disease severity. The mortality risk is increased in subjects antigen A vs non-A (OR= 3.34; 95% IC: 1.417-8.159).

Conclusion:

Blood group A is a risk factor for SARS-CoV-2 infection, but not for disease severity, although in critically ill patients it is a risk factor for mortality.