The unique health situation that we humans are currently living in at the global scale due to the COVID-19 pandemic urges scientists to gain maximum understanding about the characteristics of the new SARS-CoV-2 coronavirus, the way it contaminates individuals, and the genetic and non-genetic factors that influence our susceptibility or protection to its too often severe consequences. Little is known at the moment about specific immune mechanisms that would work against SARS-CoV-2, although such knowledge is expected to play a vital role in the absence of efficient drugs and vaccines, as is the case today. In this context, a particular focus has to be given to the human leucocyte antigen (HLA) system that governs our adaptive immunity.HLA genes are known to display the highest level of diversity of our genome, with thousands of different alleles reported nowadays, each allele being also a combination of multiple single nucleotide polymorphisms (SNPs). This unique level of polymorphism likely results from thousands of generations (since the emergence of modern humans) of HLA molecular evolution where natural selection favoured genetic variation, balancing selection in the form of heterozygous advantage (in its different versions) being the most widely accepted model. The idea of such a model is that heterozygous individuals would display a higher fitness than homozygotes in pathogen-rich environments, different HLA molecules assuming complementary abilities to present pathogen-derived peptides to T cells and elicit an immune response. The consequence of this kind of selection, at the population level, is that HLA allele frequency distributions are more even than expected under neutral evolution, most human populations displaying between 85% and 95% heterozygosity at each HLA locus.