Association Between ABO Blood Group System and COVID-19 Severity

Case-Control Study From Libya

Amina M. Bshaena, PhD; Osama H. Almajdoub, MSc; Rajaa A. Alshwesh, MSc; Entesar A. Omran, MSc; Soghra Haq, PhD; Faisal Ismail, PhD


Am J Clin Pathol. 2022;158(5):570-573. 

In This Article

Abstract and Introduction


Objectives: A possible association between blood group systems (ABO and Rh) and coronavirus disease 2019 (COVID-19) severity has recently been investigated by various studies with conflicting results. However, due to variations in the prevalence of the ABO and Rh blood groups in different populations, their association with COVID-19 might be varied as well. Therefore, we conducted this study on Libyan participants to further investigate this association and make population-based data available to the worldwide scientific community.

Methods: In this case-control study, ABO and Rh blood groups in 419 confirmed COVID-19 cases in Zawia, Libya, and 271 healthy controls were compared using descriptive statistics and χ2 tests.

Results: Blood group A was significantly more prevalent in patients with severe COVID-19 (64/125; 51.2%) than in patients with nonsevere COVID-19 (108/294, 36.7%) (P < .034), whereas the O blood group prevalence was higher in nonsevere COVID-19 cases (131/294, 44.5%) compared with severe cases (43/125, 34.4%) (P < .001).

Conclusions: The results showed a significant association between blood group A and the severity of COVID-19, whereas patients with blood group O showed a low risk of developing severe COVID-19 infection. No significant association was found between Rh and susceptibility/severity of the disease.


Since its outbreak, coronavirus disease 2019 (COVID-19) disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) continues to be a major public health threat. Globally, as of March 7, 2022, the disease has caused 440,807,756 confirmed cases, including 5,978,096 deaths.[1] In Libya, as of March 7, 2022, the cumulative cases reached 497,958 with 6,299 deaths according to the National Centre for Disease Control of Libya.[2]

Several studies have linked susceptibility to diseases with blood groups,[3] and a number of blood groups systems are recognized; however, ABO and Rh are the most widely used blood group systems in the world.[4] The association between ABO and Rh blood groups with various infectious diseases has been reported;[5] however, unlike the ABO blood group, Rh blood types are associated with fewer diseases.[6]

Recent studies from around the world have investigated the connections between ABO and Rh blood groups with SARS-CoV-2 infection. The understanding of blood group types and their relationship to COVID-19 severity might be useful in the disease management guidelines. However, as the relationship between the ABO and Rh systems may show variations between different populations,[6] their associations with COVID-19 might vary accordingly; therefore, we conducted this study to investigate this association further in Libyan participants with the primary goal of making population-based data available to outside researchers.