The major histocompatibility complex (MHC) molecule is a cell surface protein complex encoded in the human leukocyte antigen (HLA) locus . The genetic variation of the three major histocompatibility complex (MHC) class I genes (human leukocyte antigen A [HLA-A], -B, and -C genes) affect the susceptibility and severity of COVID-19 disease(55). The HLA gene complex is closely linked to genes, and there is little exchange between homologous chromosomes. HLA loci located on the same chromosome constitute a closely linked gene group (including HLA-I and II genes), called haplotype or haplotype. A haplotype is inherited as a unit. To the offspring, it is called haplotype genetics. However, HLA haplotypes are not the main risk/protective factor for SARS-COV-2 infection or severity in the Israeli population . It indicates that the genetic variation of MHC structure may protect immune cells that can bind to MHC to a certain extent.