KIR3DL1 and COVID-19: The frequency of both three Ig-domain containing inhibitory KIRs and their cognate HLA class I ligand combinations, such as KIR3DL1+HLA-Bw4+ (44.5 vs. 55.4%, p = 0.03, OR = 0.65, CI = 0.43–0.96) and KIR3DL2+HLA-A3/11+ (25 vs. 35.4%, p = 0.02, OR = 0.6, CI = 0.4–0.94), were significantly decreased in patients hospitalized with COVID-19 compared to the general population controls (Table 3).