HLA-A and COVID-19: At HLA-A and HLA-B, the allele frequencies of 80I and 80 T were decreased in severe COVID-19, while mild patients had HLA-Bw4 frequencies similar to those of controls but carried more 80I and less 80 T than controls (Figure 4B), which could be explained by the overall superior peptide-binding capacities of 80I than 80 T alleles (Figure 1E).