Chloroquine has been recommended by Chinese, South Korean and Italian health authorities for the treatment of COVID-19.[47][48] These agencies noted contraindications for people with heart disease or diabetes.[49] Both chloroquine and hydroxychloroquine were shown to inhibit SARS-CoV-2 in vitro, but a further study concluded that hydroxychloroquine was more potent than chloroquine, with a more tolerable safety profile.[50] Preliminary results from a trial suggested that chloroquine is effective and safe in COVID-19 pneumonia, "improving lung imaging findings, promoting a virus-negative conversion, and shortening the disease course."[51] Self-medication with chloroquine has caused one known fatality.[6]