GENEVA (Reuters) – The World Health Organization will resume its trial of hydroxychloroquine for potential use against the coronavirus, its chief said on Wednesday, after those running the study briefly stopped giving it to new patients over health concerns.

The U.N. agency last month paused the part of its large study of treatments against COVID-19 in which newly enrolled patients were getting the anti-malarial drug to treat COVID-19 due to fears it increased death rates and irregular heartbeats.

The study continued with other medicines.

But the WHO’s director-general, Tedros Adhanom Ghebreyesus, said its experts had advised the continuation of all trials including hydroxychloroquine, whose highest-profile backer for use against the coronavirus is U.S. President Donald Trump.

“The executive group will communicate with the principal investigators in the trial about resuming the hydroxychloroquine arm of the trial,” Tedros told an online media briefing, referring to WHO’s initiative to hold clinical tests of potential COVID-19 treatments on some 3,500 patients in 35 countries.

The WHO’s decision to suspend its trial prompted others to follow suit, including Sanofi, which said on May 29 it was suspending recruitment for its trials. A Sanofi spokesman said the company would review available information and run consultations in the coming days to reassess its position following the WHO’s latest decision on Wednesday.

The WHO’s chief scientist, Soumya Swaminathan, called for other trials of the drug to proceed. “We owe it to patients to have a definitive answer on whether or not a drug works,” she said, adding that safety monitoring should also continue.

Swaminathan said the WHO would be keen to see more results of clinical trials of Avifavir, a drug she said would be used to treat COVID-19 in Russian hospitals “very soon”.

In the same virtual briefing, WHO officials said they were especially worried about outbreaks in Latin America and in Haiti, one of the world’s poorest nations, where infections have been spreading rapidly.

The coronavirus has infected almost 3 million people in the Americas and more than 6.43 million worldwide.