Other countries including Italy, Egypt, Tunisia, Colombia, Chile, El Salvador, Cape Verde, Albania, and Bosnia and Herzegovina also banned the use of the drug for COVID-19 patients, though in Italy it remains possible in clinical trials.

Sweden had used the drug in the early phases of the pandemic to treat patients with severe symptoms, but halted its use in April after the European Medicines Agency recommended it only be used in clinical trials.

Germany, too, had judged that the current studies did not allow for the drug to be used on individual COVID-19 patients and it could only be used in clinical trials.

In the US, hydroxychloroquine can only in principle be given to COVID-19 patients in hospital, but the Food and Drug Administration (FDA) warned in April that the drug could have potential harmful impact on the heart.

The study has led to the suspension of the use of the drug in several clinical trials, including the WHO's Solidarity Trial and Europe's Discovery programme coordinated by France's Inserm research institute.