The frequencies of KIRs as HLA receptors were largely similar between patients and controls, except KIR3DL1 was underrepresented in severe cases, but the difference did not reach statistical significance (HC vs. severe: 95.4% vs. 89.6%, p = 0.170) (Table S7), and its ligand Bw4 allotypes (HLA-A and -B) were also decreased in severe COVID-19 but did not reach statistically significant (HC vs. severe: 71.9% vs. 58.3%, p = 0.051) (Table S6). This evidence concerns the gene KIR3DL1 and COVID-19.