Patient with severe COVID-19 may have exaggerated defense response causing Systemic Inflammatory Response Syndrome (SIRS). Antibody, one of immune response, not only fights foreign substances but also used as blood grouping. This study aims to determine the relationship between blood group and severity of COVID-19 symptoms. This is a retrospective descriptive study. The data was taken cross-sectionally on COVID-19 subjects confirmed RT-PCR positive with severe and non-severe degrees with blood type examination results. The secondary data were taken from the Laboratory Information System and medical records on period January-December 2020. The statistical analysis uses chi-square. From 92 subjects, the most common blood group among all COVID-19 patients (in order) is O (40,2%), A (28,3%), B (22,8%), AB (8,7%) among the severe patient group is A (37.0%) among the non-severe patient group is O (47.8%) p>0.05 while among the subject with comorbidities (76.1%) p<0.05 is A (40.0%). Anti-A antibody is more protective and it blocks the interaction between SARS-CoV-2 and ACE-2 receptor. The absence of anti-A in blood group A and AB causes these blood groups found in the severe patient group. The presence of anti-A in blood types O and B causes the majority of non-severe degree. Although there is no significant difference between severe and non-severe groups based on blood group, Anti-A antibodies are more protective and blocks the interaction between SARS-CoV-2 and the ACE-2 receptor.

COVID-19; severity; blood group ABO