On the day that new coronavirus cases across the United States hit their highest total since the pandemic began, the Senate Homeland Security Committee held a hearing on an antimalarial drug that has repeatedly been shown to be ineffective at treating covid-19.

As the country logged 185,424 daily infections Thursday, the committee spent more than two hours revisiting discussion about hydroxychloroquine as a potential covid-19 treatment — a debate that leading health experts say was settled months ago.

Study after study has shown that the drug touted by President Trump and his allies as a solution to the pandemic is ineffective in protecting patients against the virus. Top health officials in the Trump administration, including Anthony S. Fauci and Deborah Birx, have said clinical trials show the drug is unhelpful.

Committee Chairman Ron Johnson (R-Wis.) returned to the issue anyway, calling a panel of witnesses who have publicly supported the drug. He repeatedly criticized the medical community, suggesting at one point that it had “censored” evidence that hydroxychloroquine could work and that federal scientific agencies may have “turned a blind eye” toward the treatment because of Trump’s promotion of it.

Johnson also wondered aloud whether doctors and medical experts were backing another drug, remdesivir, over hydroxychloroquine because remdesivir sales bring in more money for pharmaceutical companies.

“I question the fact that because this cocktail costs about $20 and remdesivir costs $3,000, that maybe there’s a little bias, maybe there’s a little conflict, maybe there’s a little agenda,” he said.

The Food and Drug Administration withdrew its emergency-use authorization for hydroxychloroquine in hospitalized patients in June, concluding that safety risks, including heart problems, outweighed any potential benefits. It has also warned against using the drug in outpatient settings, saying it could cause serious heart rhythm problems.

The first randomized clinical trial later found that hydroxychloroquine was no more effective than a placebo at treating covid-19 in patients who were not hospitalized.

Ashish Jha, dean of Brown University School of Public Health, testified in support of those findings that “dozens of studies” failed to find any benefit to hydroxychloroquine. The “clear consensus in the medical and scientific community, based on overwhelming evidence,” is that it does not work, he said.

“Hydroxychloroquine is a cheap and widely available medicine,” said Jha, who was chosen to testify by ranking Democrat Gary Peters (Mich.). “Had it been effective, it would have made an enormous difference in this pandemic. Unfortunately, it isn’t effective, and it has not made a difference."

Still, the three witnesses selected by Johnson expressed strong support for using hydroxychloroquine in outpatient settings.

“This drug is extremely safe, exceedingly safe,” said Harvey Risch, a professor of epidemiology and public health at Yale University. “We know this from common sense. This is a medication that’s been used for 65 years by hundreds of millions of people in tens of billions of doses worldwide.”

Risch has advocated for the use of hydroxychloroquine at least since May, when he published a paper in support of it. More than two dozen of his colleagues responded in August with a letter expressing concern that Risch, whose research focuses on cancer and not infectious diseases, was not swayed by data refuting his arguments.

George Fareed, a family medicine specialist in Brawley, Calif., testified that he had effectively treated covid-19 patients with hydroxychloroquine. He had previously written to the Trump administration to urge it to promote the use of the drug within the first five days of a patient’s illness.

The two other Republican senators who spoke, Mike Enzi (Wyo.) and James Lankford (Okla.), asked about early treatments without directly expressing support for hydroxychloroquine. Most Democrats ignored the topic and used their time to highlight other pandemic issues, including Americans’ willingness to accept a future vaccine and small gatherings driving the spread of the virus.

But the hearing’s most contentious moments came when the witnesses contradicted each other on the efficacy of hydroxychloroquine, including when Peter McCullough, vice chief of internal medicine at Baylor University Medical Center, testified that Jha’s opposition to the drug was “reckless and dangerous for the nation.” He said Jha was promoting misinformation by expressing concern about the drug’s safety.

Reflecting on the hearing afterward, Jha said it was “stunning” because it pushed the view that mitigation measures such as wearing masks and maintaining social distance are unimportant because the illness can easily be treated with hydroxychloroquine.

“I tried to explain that doctors don’t want to kill their patients by withhold[ing] therapy,” he tweeted. “But evidence matters They tried to flip the narrative: that evidence was misinformation And ‘art of medicine’ was what mattered.”

Jha added: “The hearing was a testament to how politicized science has become."

Derek Hawkins contributed to this report.