Chloroquine is reasonably active in vitro against SARS‐CoV‐1, MERS‐CoV, and SARS‐CoV‐2. It was found to inhibit SARS‐CoV‐2 with an EC50 value of 5.47 µM in vitro. 66  Antiviral activity against SARS‐CoV‐1 was reported with an IC50 of 8.8 μM in Vero cells, but it is unclear how this translates into activity in respiratory epithelial cells and in vivo. 67 ,  68  Mechanistic studies of chloroquine for SARS‐CoV‐1 infection revealed that it could also weaken the interaction between the RBD of SARS‐CoV‐1 and ACE2 by interfering with terminal glycosylation of ACE2, thereby reducing its affinity to SARS‐CoV‐1 S. 69