KIR3DL1 and COVID-19: In fact, all inhibitory functional units examined were found to have higher frequencies in COVID-19 patients than in the population group (KIR2DL1/HLA C2 group 74.2% vs 69.5%, KIR2DL2/HLA C1 group 44.7% vs 44.5%, KIR2DL3/HLA C1 group 67.4% vs 64.8%, KIR3DL1/HLA Bw4 epitope 72.7% vs 70.5% and KIR2DL2-3/HLA C1 group 40.2% vs 34.3%).