Furthermore, genetic polymorphisms of human leukocyte antigens (HLAs) have been identified to influence the susceptibility to various viral diseases, including SARS-CoV-2, MERS-CoV-2, influenza, dengue, and hepatitis B. Genetic variations in HLAs are also significantly associated with the susceptibility to and severity of COVID-19, thereby playing a crucial role in identifying groups at higher risk of COVID-19 disease [76,77,78]. Here, HLA-S is linked to viral load.