Are Blood Groups Protective Against COVID-19?

Blood Types and Severity of COVID-19

Aim: Since blood types first appeared, their association with diseases caused by microorganisms has been further investigated with several studies for many years. The bond of blood groups described as A, B, AB, and O with coronavirus has been the research subject in many countries.We aimed to elucidate whether there was a relationship between blood types and Rh factor and contracting COVID-19 disease and disease severity. Methods: The study was designed as a retrospective case-control study. Between March 2020 - February 2021, 1110 patients were included (538 cases, 572 controls). Disease severity was classified according to where patients were treated: those who were outpatients considered as “mild disease”, hospitalized in a hospital ward considered as “moderate disease”, and treated in the intensive care unit were considered as “severe disease”. Results: The number of people with blood type A was 447 (40.3%), blood type B was 197 (17.7%), blood type AB was 90 (%8), and blood type O was 376 (33.9%). There was no significant difference between the case and control groups according to the blood types. A 3.93 times increase of developing mild illness was detected compared to the control group in Rh-positive individuals. The rate of developing a severe disease was higher in females with blood type A than a mild disease, and A blood type caused the disease to be severe compared to other blood groups in females. Conclusion: We concluded that blood type A caused more severe disease than other blood types in females, and females with B blood type survived the disease as outpatients. Our study can shed light on pathophysiological investigation of the relationship between COVID-19 disease causing a pandemic with high mortality and virulence and blood types. Keywords: COVID-19 virus, blood group, disease