Relationship between ABO blood group and COVID-19 infection

Introduction: The Coronavirus is the causal agent of severe acute respiratory syndrome (SARS-CoV-2), which in 2020 led to suffering, hospitalization, and the deaths of many patients. Given the magnitude of this event, research began early on into some risk factors that could be associated with increased susceptibility, morbidity, and mortality from this disease. Among these factors, the relationship with individuals' ABO blood group was studied. This paper aims to review the existing evidence regarding the association between blood group and the risk of susceptibility, complications, and mortality in individuals infected with COVID-19. A systematic review will be conducted of some articles and scientific papers published in the last five years that relate ABO blood group to susceptibility, severity of complications, and mortality in individuals infected with COVID-19. Immunoglobulin G present in the serum of individuals with blood group O provides greater protection against the virus and allows for an early and regulated release of pro-inflammatory cytokines. The analyzed studies indicate that blood group O is associated with a lower number of severe cases, whereas blood group A presents a higher number. The susceptibility to infection is lower in blood group O. Mortality data vary among the studies reviewed. The results suggest that blood group A could be considered a risk factor concerning mortality and susceptibility to this disease. However, more extensive studies involving larger populations are needed to confirm these findings.