In-vitro studies have shown that chloroquine is effective against several viruses, including severe acute respiratory syndrome coronavirus (SARS-CoV).1 Multiple mechanisms of action have been identified for chloroquine that disrupt the early stage of coronavirus replication. Moreover, chloroquine affects immune system activity by mediating an anti-inflammatory response, which might reduce damage due to the exaggerated inflammatory response.1 At the time of the SARS epidemic, chloroquine was suggested as a drug that could be used to treat this infection.2 However, randomised, double-blind, controlled studies in humans to evaluate its efficacy for this use were not done, and the true clinical efficacy of chloroquine in treating coronavirus infections was not established.