On the back of mounting concerns about hydroxychloroquine's safety, global pharmaceutical major Sanofi (NASDAQ:SNY) has quit providing it to COVID-19 patients enrolled in its clinical trials for the drug. It has also put a temporary halt on recruiting new subjects for the research.

Hydroxychloroquine, originally designed to treat malaria, was formerly considered a potential treatment for COVID-19, the disease that can result from the SARS-CoV-2 coronavirus. It had some high-level support, most notably from President Donald Trump, who at one point claimed he was regularly taking it.

A coronavirus colony.

Image source: Getty Images.

The pharmaceutical giant's decision follows the World Health Organization's (WHO's) stoppage of its own clinical trials on hydroxychloroquine and the subsequent banning of the drug's use by several European countries. The source of its concern is a recent paper published in U.K. medical journal The Lancet, indicating increased death rates from taking the medication.

That paper, which is based on an analysis of medical records, is not the only research that has found the drug might not be appropriate for COVID-19 patients. Last month, a similar analysis of 368 U.S. veterans also indicated elevated death rates in patients receiving the treatment.

Two randomized, controlled clinical trials were being conducted by Sanofi to test hydroxychloroquine's efficacy in fighting COVID-19. One was a multinational study involving 210 patients presenting an early stage of the disease. These individuals had not been hospitalized. The other, larger one involved roughly 300 people suffering from moderate to severe forms of the disease who had been hospitalized; this was limited to Europe.

On Friday, shares of Sanofi inched up by 0.9%, roughly in line with the performance of the wider stock market on the day.

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