The S2 subunit, which encompass the fusion system, is divided by the transmembrane serine protease 2 (TMPRSS2), a protease manifested by epithelial cells of the respiratory tract.66 This serine protease with trypsin-like activity is then released into the extracellular space, where it may activate the membrane bound PAR2, which is expressed by several cells in the lung and is involved in inflammation.67 Recently, nafamostat mesylate and camostat mesylate, TMPRSS2 inhibitors,34,66 have currently been studied in patients with COVID-19. Here, TMPRSS2 is linked to COVID-19.