ABO Blood Group is Associated with COVID-19 Susceptibility: a Systematic Review

Introduction: Conflicting evidences exist that ABO blood groups correlate with the susceptibility to COVID-19 and its clinical outcomes. This study aimed to pool available articles that assessed a possible relationship between COVID-19 and ABO blood groups. Materials and methods: A search was conducted in four databases comprising Pubmed/Medline, Google scholar, Journal storage (JSTOR) and African Journals Online (AJOL) for relevant studies available before 25th August 2020 and contained extractable data on ABO blood type distribution and COVID-19 disease. Search terms included a combination of “ABO blood group, and COVID-19, coronavirus, and SARS-COV-2”. Results: Fourteen articles that met study inclusion criteria were selected from a total of five hundred and eighty-five articles identified through database search. The fourteen articles reviewed comprised of a total of 73934 subjects (13189 SARS-COV-2 positive cases and 60745 controls). Overall, the risk of SARS-COV-2 infection was found to be significantly increased in patients with blood group A with ORs: 1.24 (95%Cl: 1.09-1.41, P = 0.001). Additionally, blood group O subjects were seen to have decreased odds of contracting COVID-19 infection (OR: 0.78, 95%Cl: 0.68 – 0.89, P=0.0003). No significant association was found between ABO blood groups and COVID -19 severity and mortality. Conclusions: Blood group A was associated with a higher risk of SARS-COV-2 infection whereas risk of infection was lower in blood group O subjects. No statistical significant association was found between ABO blood groups and COVID-19 severity and mortality. The precise role of ABO blood group in COVID-19 susceptibility, severity and mortality requires further research for clarification