HLA-DRB1 and COVID-19: For MHC class II, the frequency of HLA-DRB1*11:02 was higher in COVID-19 patients compared to controls (2.86% vs. 0.34%, p < 0.001) (Figure 1), while the frequency of DQB1*03:03 was lower in the patients group (2.86% vs. 9.04%, p < 0.001).