Many studies report that blood type A might predispose one to increased susceptibility of infection with SARS-CoV-2, and type O and Rh-negative blood groups might be protective.
Relationship between blood type and outcomes following COVID-19 infection
Blood type has been identified as a risk factor in many disease processes, ranging from malignancy to venous and arterial thromboembolism. The most widely studied associations, however, have been in the realm of infectious diseases. Blood group antigens play a direct role in infection through various mechanisms. On a molecular level, they can serve as receptors and coreceptors for pathogens; and can also facilitate intracellular uptake of viral particles. Clinically, blood types have been linked to bacterial, parasitic, and viral infections
Eight of 9 studies demonstrated an association between blood type and susceptibility to infection with SARS-CoV-2. Four of these 9 studies also revealed an association with severity of illness. Ray et al [21] found that subjects with type O and Rh-negative blood were protected from viral infection, severe illness, and mortality.
All studies were limited
an increased risk of infection with type A blood.
Four of 5 studies found significant associations with Rh-negative blood grouping. Both Ray et al [21] and Zietz et al [23] found that subjects with Rh-negative blood type were at lower risk of viral infection, severe illness, and mortality after infection. Our study, along with Leaf et al's [19], also found that Rh-negative subjects were at lower risk of infection, but did not find any impact on COVID-19–related illness or mortality. Although overall results might be mixed, there is a consistent theme on Rh-type and susceptibility to COVID-19 infection.
As mentioned previously, Hoiland et al [17] reported an association with blood types A and AB with worse clinical outcomes
Many studies report that blood type A might predispose one to increased susceptibility of infection with SARS-CoV-2, and type O and Rh-negative blood groups might be protective. Although this appears to be an emerging trend, the impact of blood type on clinical outcomes remains unclear.
Testing the association between blood type and COVID-19 infection, intubation, and death
Recent evidence suggests blood type may affect risk of severe COVID-19. We used observational healthcare data on 14,112 individuals tested for SARS-CoV-2 with known blood type in the New York Presbyterian (NYP) hospital system to assess the association between ABO and Rh blood types and infection, intubation, and death. We found slightly increased infection prevalence among non-O types. Risk of intubation was decreased among A and increased among AB and B types, compared with type O, while risk of death was increased for type AB and decreased for types A and B. We estimated Rh-negative blood type to have a protective effect for all three outcomes. Our results add to the growing body of evidence suggesting blood type may play a role in COVID-19.
In this study we found evidence for associations between ABO and Rh blood groups and COVID-19. Using data from NYP/CUIMC, we found moderately increased infection prevalence among non-O blood types and among Rh-positive individuals. Intubation risk was increased among AB and B types, and decreased among A and Rh-negative types. Risk of death was slightly increased among type AB individuals and was decreased among types A, B, and Rh-negative types. All estimates were adjusted for patient ancestry using self-reported race and ethnicity. Our results add further evidence to the previously discovered associations between blood types and COVID-19.
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7276013/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8286549/