But a new analysis of the drug’s use in the early stages, not yet reviewed as part of the typical scientific peer-review process, found a higher rate of death among patients who used hydroxychloroquine compared to those who received standard care.
Questioned by ABC News Chief White House Correspondent Jonathan Karl about the new findings on Tuesday, the president said he was unaware of the report.
“Obviously, there have been some very good reports and perhaps this one is not a good report. But we'll be looking at it,” Trump told Karl.
Tune into ABC at 1 p.m. ET and ABC News Live at 4 p.m. ET every weekday for special coverage of the novel coronavirus with the full ABC News team, including the latest news, context and analysis.
The study, which analyzed the care of 368 patients in veterans hospitals across the country, represents one of the largest analyses to date of the use of hydroxychloroquine with or without the antibiotic azithromycin.
According to the study’s findings, the rate of death among patients who used hydroxychloroquine was 28% compared to an 11% death rate among patients who received standard care and did not use hydroxychloroquine. Those patients who were treated with hydroxychloroquine along with azithromycin died a rate of 22%.
Infectious disease experts told ABC News that while noteworthy, the study was still relatively small, and that the fact that it was not randomized or peer-reviewed meant that no firm conclusions could be reached.
Separately, this week, a panel of doctors and other experts convened by the National Institutes of Health recommended against using hydroxychloroquine and azithromycin together to treat COVID-19, unless they were being used as part of a clinical trial.
The Infectious Diseases Society of America also recommends against giving patients combinations of hydroxycloroquine, the similar drug chloroquine, or azithromycin unless enrolled in a clinical trial.
"The combination of hydroxychloroquine and azithromycin was associated with QTc prolongation in patients with COVID-19," the NIH panel wrote.
QTc refers to a measurement of heart rhythm; if the rhythm becomes too prolonged, patients could suffer sudden cardiac death.
Scientists in Brazil aborted a study with the drug earlier this month after heart rhythm problems developed in one-quarter of the patients who were given the higher of two doses being tested.
Trump has repeatedly suggested that people combine the two drugs, both in briefings at the White House and on Twitter.
"HYDROXYCHLOROQUINE & AZITHROMYCIN, taken together, have a real chance to be one of the biggest game changers in the history of medicine," he tweeted on March 21.
Infectious disease experts told ABC News that, while the study was helpful, it did not replace more rigorous clinical trials, currently ongoing across the country. The Food and Drug Administration has said those findings won’t be available until early summer.
"We need randomized, controlled trials to further evaluate this, but it also is a cautionary note to us as physicians that we need to take a closer look before we prescribe these meds," said Simone Wildes, an infectious diseases physician in Weymouth, Mass., who is also an ABC News medical contributor. "We just need to be a little bit more cautious now."
The president had persisted in his promotion of the promise of hydroxychloroquine by highlighting anecdotal stories of success when the drug has been used, even as the nation’s top infectious disease expert Dr. Anthony Fauci has said there is no scientific evidence to support an endorsement of the drug.
“The answer is no,” Fauci told a reporter bluntly, while standing beside the president, when questioned about the drug’s potential promise.
“The information that you’re referring to specifically is anecdotal,” Fauci told the reporter. “It was not done in a controlled clinical trial. So you really can’t make any definitive statement about it.”
Earlier this month, the president even appeared to block Fauci from further contradicting him when a reporter sought to ask Fauci again whether there is any evidence of the drug’s success, in light of the president’s continued promotion of the drug.
“Do you know how many times he’s answered that question? Maybe 15,” Trump interjected before Fauci, who was standing at the podium, could answer the reporter’s question.
The briefing then moved on to other questions, without Fauci ever answering the question.
“If it doesn’t work, it’s nothing lost by doing it. Nothing,” Trump said that day in promoting the application of the drug as low-risk.
But without knowing the results of larger clinical trials -- which are likely months away -- doctors will not know for sure what the benefits or risks could be, according to William Schaffner, a professor in the division of infectious diseases at Vanderbilt University, in Nashville.
"It's only when we get that kind of rigorous investigation," Schaffner told ABC News, "that we will be able to speak confidently with our patients about what to expect when drugs like this are used."
This report was featured in the Thursday, April 23, 2020, episode of “Start Here,” ABC News’ daily news podcast.
"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.