HLA-DRB1 and COVID-19: The protective effect of the HLA-A*02:01, B*18:01, DRB1*03:01 extended haplotype in the Ne group of patients became even more apparent when distinguishing between patients with asymptomatic/pauci-symptomatic/moderate (Nep) or severe (Nes) forms of COVID-19 (Figure 2).