The impact of ABO and Rh(D) blood group on Covid-19 immune response.

Previous studies indicate that blood type O has a protective effect against Covid-19 disease. In the present study, we aimed to further explore and clarify the connection between ABO blood groups and the Covid-19 disease by examining the levels of Covid antibodies in patients with different ABO blood types. During the first pandemic year, and before the vaccine was available, SARS-CoV-2 antibody level were randomly analyzed at the regional hospital laboratory and the data was stored in the laboratory information system (LIS) Flexlab/Chemistry. The investigated cohort was created by cross-referencing the SARS-CoV-2 antibody results with the ABO Rh(D) blood group status available in the LIS Prosang. The association between antibody level and blood group was further analyzed within this cohort. There was a significantly higher odds of Covid positivity among individuals in the cohort with blood type A or AB compared to blood type O. There was no significant difference in odds of Covid positivity among between phenotypes B compared to blood type O. The quantitative levels of SARS-CoV-2 antibodies were similar in individuals with a positive Covid-19 test regardless of ABO and Rh(D) phenotype. The present cohort study supports the hypothesis that the presence of anti-A antibodies in serum should be considered as a factor more significant than the blood group itself. However, the study showed a similar immune response in individuals with a positive Covid-19 test regardless ABO phenotype.