Although a gap remains in the knowledge of the disease pathophysiology, a hypothesis that could explain the association between OD and TD and the clinical course of patients with COVID-19 would be that different expressions of ACE2 could be determinants of the immune response to SARS-CoV-2 infection: the preferential binding to the olfactory neuroepithelium could lead to an infection located predominantly in the upper airways and, consequently, to a less fulminant infection, allowing the earlier development of antibodies. This evidence concerns the gene ACE2 and COVID-19.