The World Health Organization (WHO) said Monday that due to safety concerns, it is temporarily halting a clinical trial of the anti-malaria drug hydroxychloroquine for treating coronavirus patients.

The announcement follows the publication Friday by the Lancet medical journal of an observational study on hydroxychloroquine and chloroquine and its effects on hospitalized COVID-19 patients.
"The Executive Group has implemented a temporary pause of the hydroxychloroquine arm within the Solidarity Trial while the safety data is reviewed by the Data Safety Monitoring Board," said WHO Director-General Tedros Adhanom Ghebreyesus.
He said that more than two months ago, the WHO initiated its "Solidarity Trial" to evaluate the safety and efficacy of four drugs and drug combinations against COVID-19.
On April 19, US President Donald Trump said he had been taking hydroxychloroquine, which he has repeatedly touted for the treatment of coronavirus patients.
"A lot of good things have come out about the hydroxy. You'd be surprised at how many people are taking it, especially the frontline workers," Trump said at the White House. "I happen to be taking it. I'm taking it, hydroxychloroquine. Right now."
More than 400 hospitals in 35 countries are actively recruiting patients, and nearly 3,500 patients had been enrolled from 17 countries to test the drug, said the WHO.
The study published in the Lancet peer-reviewed journal looked at over 96,000 virus patients.
It found a higher risk of abnormal heartbeats, or arrhythmias, that could cause a heart attack in those treated with hydroxychloroquine or chloroquine.
The Lancet study looked at patient medical records in 671 hospitals across six continents, making it the most extensively published evaluation of the drug's impacts on coronavirus patients.
Tedros said the Lancet report researchers found a higher mortality rate among patients receiving the drug when used alone or with a macrolide.
"I wish to reiterate that these drugs are accepted as generally safe for use in patients with autoimmune diseases or malaria," said Tedros.
The Executive Group of the WHO's Solidarity Trial, representing 10 of the participating countries, met Saturday and agreed to review a comprehensive analysis and critical appraisal of all evidence available globally.
"The review will consider data collected so far in the Solidarity Trial and, in particular, robust randomized available data to adequately evaluate the potential benefits and harms from this drug," said the WHO chief.
Dr. Mike Ryan, executive director of the WHO’s health emergencies program, said: “We're just acting on an abundance of caution based on the recent results of other studies to ensure that we can continue safely with that arm of the trial.”