A Cross-Sectional Study of the Association of ABO Blood Group and Rh Type With Severity of COVID-19 Infection in a Tertiary Care Center of South India.

Background The novel coronavirus disease 2019 (COVID-19) was declared a pandemic that had affected 224 countries, causing >2.1 million deaths worldwide. The association of the different ABO blood groups with the risk and severity of COVID-19 infections has been speculated in many studies. This study aims to determine the incidence of COVID-19 infections among various blood groups and the association of ABO blood groups and Rh type with the severity of COVID-19 infection as well as with other outcome predictors of COVID-19 infection including neutrophil-to-lymphocyte ratio, D-dimer, ferritin, lactate dehydrogenase, and C-reactive protein. Methodology This was a retrospective study conducted among 150 serologically positive patients >18 years of age who underwent treatment in a district government hospital over two months. Patients were categorized into severity groups, and laboratory data were divided into those corresponding to severe disease and otherwise, in accordance with national guidelines. Appropriate statistical analysis was performed. Results The frequency of blood groups A, B, AB, and O was 30.7%, 29.4%, 13.7%, and 39%, respectively. There was a statistically significant number of patients belonging to non-O blood groups who developed a severe COVID-19 infection (group C) (p = 0.005). There was an increased risk of multiorgan failure (p = 0.035), non-invasive ventilation (p = 0.005), intubation, and mortality among non-O blood groups, and was the maximum for A blood group even after adjusting for age and pre-existing comorbidities. Increased D-dimer levels were noted in non-O blood groups (p = 0.037). No statistically significant association was found between Rh typing and the severity of COVID-19 infection. Conclusions Our findings provide evidence that individuals with non-O blood groups are susceptible to developing more severe COVID-19 infections and should take active preventive measures. Moreover, they should be cautiously monitored and treated once infected.