We found that the SARS-CoV-2 inhibitory activity of camostat and nafamostat were lost when infections were performed in TMPRSS2-negative Vero E6 cells, suggesting that these compounds likely work through inhibition of TMPRSS2 protease activity rather than through direct virucidal action (see Fig. S1 in the supplemental material). The gene discussed is TMPRSS2; the disease is infection.