Figure 1.

Schematic overview of the role of the nasal mucosa in COVID-19. The panel depicts the epithelial lining of the nasal mucosa expressing the entry receptors for SARS-CoV-2, and the associated microbiota and immune cells. In the presence of a healthy mucosa, the response to the virus is protective. On the contrary, in the presence of an impaired mucosa, the homeostasis is lost and alterations in microbiota, barrier integrity, and immune response turn the viral infection into overt disease. Details are described in the text.