ABO Blood Group Association with COVID-19 Susceptibility

The ABO blood group system, defined by the presence or absence of A and B antigens on erythrocyte surfaces, has emerged as a modest but consistent factor influencing susceptibility to SARS-CoV-2 infection and clinical outcomes. Across diverse populations, individuals with blood group O generally exhibit a slightly lower likelihood of contracting COVID-19, whereas non-O groups—particularly type A—tend to show elevated infection rates and, in some studies, increased risk of severe respiratory complications. Proposed mechanisms include natural anti-A and anti-B antibodies interfering with viral attachment, as well as differences in coagulation profiles linked to variations in von Willebrand factor levels and thrombotic tendency. Although the effect sizes are relatively small at the individual level, the global distribution of blood groups implies a significant public-health impact through population-level modulation of transmission dynamics and risk stratification. Integrating ABO status into epidemiological models and considering blood-group distributions among convalescent plasma donors may refine preventive strategies and resource allocation in future outbreaks.

Research from Nature Portfolio

Large observational analyses have clarified the influence of ABO and Rh blood types on COVID-19 outcomes. In a seminal study of over 14 000 tested individuals, non-O blood groups displayed a marginally higher infection prevalence, with blood group A linked to reduced intubation risk but group AB and B showing increased risk; mortality was elevated in AB and lower in A and B, while Rh-negative status conferred modest protection across endpoints. Complementary work in a Bahrain cohort examined over 500 infections and found blood group B associated with greater infection risk and AB with lower risk, without significant effects on intensive care admission. Neither study supported a decisive role for antibody class in predicting severe disease, underscoring a complex interplay between antigen expression and host factors beyond simple serological classification.

ABO Blood Group Association with COVID-19 Susceptibility publication trend

The graph below shows the total number of articles in abo blood group association with covid-19 susceptibility across all publications each year (not limited to Nature Index journals).

Technical terms

ABO blood group: A classification of human blood based on the presence or absence of A and B carbohydrate antigens on red blood cells.

Antigen: A molecular structure, often on cell surfaces or pathogens, that is recognised by the immune system and can elicit an antibody response.

Antibody: A protein produced by B lymphocytes that binds specifically to a complementary antigen and mediates immune defence.

Odds ratio: A statistical measure expressing the likelihood of an outcome occurring in one group relative to another.

Convalescent plasma: Plasma collected from individuals who have recovered from an infection, containing antibodies that may confer passive immunity.

Thrombosis: The formation of a blood clot within a vessel, which can contribute to organ dysfunction in severe COVID-19.

References

1. Associations between blood type and COVID-19 infection, intubation, and death. Nature Communications (2020).
2. The effect of ABO blood group and antibody class on the risk of COVID-19 infection and severity of clinical outcomes. Scientific Reports (2021).
3. Blood Group Variations in COVID-19 Convalescent Plasma and Regular Blood Donors: A Comparative Analysis in the Serbian Population. Microorganisms (2024).
4. The association between ABO blood group and SARS-CoV-2 infection: A meta-analysis. PLOS ONE (2020).
5. ABO Blood Types and COVID-19: Spurious, Anecdotal, or Truly Important Relationships? A Reasoned Review of Available Data. Viruses (2021).
6. Harnessing the natural anti-glycan immune response to limit the transmission of enveloped viruses such as SARS-CoV-2. PLOS Pathogens (2020).