Nearly 17,000 people may have died after taking hydroxycholoroquine during the first wave of COVID, according to a study by French researchers.

The anti-malaria drug was prescribed to some patients hospitalized with COVID-19 during the first wave of the pandemic, “despite the absence of evidence documenting its clinical benefits,” the researchers point out in their paper, published in the February issue of Biomedicine & Pharmacotherapy.

Now, researchers have estimated that some 16,990 people in six countries — France, Belgium, Italy, Spain, Turkey and the U.S. — may have died as a result.