The World Health Organization announced on Monday that it's suspending a trial of hydroxychloroquine in treating COVID-19, saying fears of the drug's potential danger is causing it to "err on the side of caution."
The medication, best known for use against malaria and autoimmune disorders, has been touted as a possible answer to COVID-19 by President Donald Trump.
But WHO Director-General Tedros Adhanom Ghebreyesus said evidence has shown harmful side effects of hydroxychloroquine, including heart problems.
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Tedros cited the British journal The Lancet, which published findings on Friday, showing that hydroxychloroquine does not help COVID-19 patients and might even increase deaths.
"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. The other arms of the trial are continuing,” Tedros told an online briefing from Geneva.
Dr. Soumya Swaminathan, WHO's chief scientist, said the organization's own investigators and regulators in individual nations have raised enough red flags about hydroxychloroquine to prompt this halt.
"So the steering committee met over the weekend and decided that in the light of this uncertainty, that we should be proactive, err on the side of caution, and suspend enrollment, temporarily, into the hydroxychloroquine arm," she said.
WHO will take at least another week, perhaps two, to gather more data on hydroxychloroquine, Swaminathan said.
"We want to use hydroxychloroquine if it is safe, if it reduces mortality, reduces the length of hospitalization, without increasing the adverse events," she added. "So this is a temporary measure."
Tedros told patients taking the medication for its well-established uses outside of COVID-19 that they shouldn't worry.
"This concern relates to the use of hydroxychloroquine and chloroquine in COVID-19," he said. "I wish to reiterate that this drug is accepted as generally safe for use in patients with autoimmune diseases and malaria."
When Trump began touting hydroxychloroquine in March, it caused a brief run on the drug, leaving some patients using it for lupus, rheumatoid arthritis and other autoimmune diseases unable to get their medication.