More functional studies are needed to directly address the involvement of T- and NK-cell-mediated anti-SARS-CoV-2 immune responses in the whole process of viral infection and replication, and it will be of interest to elucidate the contribution of HLA-I/viral peptide-mediated CTL and HLA-I/KIR-mediated NK cell licensing to COVID-19 outcomes in different ethnic populations. The gene discussed is KIR3DL1; the disease is viral infectious disease.