The HIV‐protease inhibitor nelfinavir (183; Figure 39) strongly inhibited replication of SARS‐CoV‐1 in Vero cells with an EC50 value of 0.048 µM. It was suggested to exert its effect at the post‐entry step of SARS‐CoV‐1 infection. 250  Recently, Yamamoto et al reported that nelfinavir also potently inhibited replication of SARS‐CoV‐2 among nine other Anti‐HIV drugs tested (IC50, 1.13 µM; CC50, 24.32 µM; SI = 21.52). 251  The measured serum concentrations of nelfinavir were 3–6 times higher than the reported EC50 of this drug. This indicates that it is a promising drug candidate for the management of COVID‐19. Other drugs tested against SARS‐CoV‐2 replication were amprenavir (EC50, 31.32 µM; CC50 > 81 µM; SI > 2.59), darunavir (EC50, 46.41 µM; CC50 > 81 µM; SI > 1.75), and indinavir (EC50, 59.14 µM; CC50 > 81 µM; SI > 1.37). Tipranavir inhibited SARS‐CoV‐2 replication as well (EC50, 3.34 µM; CC50, 76.80 µM; SI = 5.76). Ritonavir (EC50, 8.63 µM; CC50, 74.11 µM, SI = 8.59), saquinavir (EC50, 8.83 µM; CC50, 44.43 µM; SI = 5.03), and atazanavir (EC50, 9.36 µM; CC50 > 81 µM; SI > 8.65) suppressed SARS‐CoV‐2 at less than 10 µM. Lopinavir, which was studied in SARS and COVID‐19 patients, also potently inhibited SARS‐CoV‐2 replication with the highest selectivity index (EC50, 5.73 µM; CC50, 74.44 µM; SI = 12.99).