WASHINGTON – A reporter's question about hydroxychloroquine led to a testy moment at Sunday's White House briefing.

Anthony Fauci was asked his thoughts on the effectiveness of the anti-malaria drug in treating coronavirus patients, and President Donald Trump interrupted before the director of the National Institute of Allergy and Infectious Diseases could answer.

“He’s answered that question 15 times,” said Trump, who had spent much of the news conference touting the drug's potential.

Earlier in the day, Fauci did answer a question about hydroxychloroquine when he was on CBS's "Face the Nation."

“The data are really, just, at best, suggestive,” he said. “There have been cases that show there may be an effect and there are others to show there's no effect. So, I think in terms of science, I don't think we could definitively say it works.”

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The differing opinions aren't new.

Fauci and White House trade adviser Peter Navarro got in a heated argument Saturday over hydroxychloroquine, according to Axios and the New York Times.

According to the reports, Navarro brought in studies from trials overseas that show the drug, which is often used to treat malaria, was working to combat coronavirus.

Fauci maintained that there is still only anecdotal information and that more rigorous studies need to be done to see the true effect of the drug, according to the reports. Despite the two arguing about the drug as a treatment, the White House coronavirus task force has agreed to surge the supply of hydroxychloroquine to hot zones.

Fauci also conceded in an interview with Science magazine in mid-March that he and Trump "disagree on some things" but that the president listens and "goes his own way." Fauci at times has been absent from some of the briefings. When he's not present, that sometimes fuels speculation about his relationship with Trump.

Both Fauci and Trump have dismissed speculation that he does not attend some of the briefings because they are on bad terms.

In addition, Fauci now has security detail after receiving threats, according to media reports. The expert has drawn criticism from some of Trump's staunchest allies online who accuse him of contradicting the president.

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According to the CDC, “There are no US Food and Drug Administration (FDA)-approved drugs specifically for the treatment of patients with COVID-19.”

The FDA’s website also has an answer for people who ask if they should take chloroquine or hydroxychloroquine to prevent or treat coronavirus.

“No,” an answer on the FDA’s FAQ about coronavirus says. “Hydroxychloroquine and chloroquine are available in the United States by prescription only for the prevention or treatment of malaria and certain inflammatory conditions such as lupus. The FDA is working closely with other government agencies and academic centers to determine whether chloroquine can be used to prevent COVID-19 or treat patients with mild-to-moderate COVID-19."

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Contributing: Nicholas Wu and Deirdre Shesgreen