Furthermore, analysis using human ACE2-transgenic rodent experimental models in which IFNAR2 and TYK2 genes are deleted or overexpressed in a cell-selective manner may also be useful for better understanding the functional mechanisms of these genes in the pathogenesis of COVID-19 caused by wild-type and mutant strains of SARS-CoV-2. This evidence concerns the gene TYK2 and COVID-19.