In all three diseases, SARS (SARS CoV virus), MERS (SARS CoV virus) and Covid-19 (SARS CoV-2 virus) the coronavirus attaches onto the ACE-2 receptor. There was a study done on SARS CoV virus and chloroquine.
Results: We report, however, that chloroquine has strong antiviral effects on SARS-CoV infection of primate cells. These inhibitory effects are observed when the cells are treated with the drug either before or after exposure to the virus, suggesting both prophylactic and therapeutic advantage.
From this study:
Chloroquine Is a Potent Inhibitor of SARS Coronavirus Infection and Spread
Martin J Vincent et al. Virol J. 2005
https://pubmed.ncbi.nlm.nih.gov/16115318/
