At the height of Fox News’s coverage of a would-be treatment for the novel coronavirus, the network’s medical correspondent, Marc Siegel, offered a remarkable testimonial during Tucker Carlson’s show.

Siegel said his 96-year-old father, suffering from symptoms of the virus and fearing he would die, made a full recovery thanks to the drug, hydroxychloroquine, and a course of antibiotics. “He got up the next day and was fine,” Siegel told an astonished Carlson.

Siegel’s miraculous-recovery story was part of a near-campaign for hydroxychloroquine by Fox News and its sister network, Fox Business.

Echoing President Trump’s description of the drug as a “game changer,” Carlson, Laura Ingraham, Sean Hannity, Lou Dobbs and “Fox and Friends” hosts spoke of its potential benefits in dozens of segments from mid-March to mid-April. They also criticized those in the media and the medical establishment who raised concerns, turning a debate among researchers and scientists into another front in the culture wars.

But in the past week or so, Trump has all but stopped talking about hydroxychloroquine. And so have Fox News’s hosts.

The relative silence follows disappointing, even alarming, new research about hydroxychloroquine as a treatment for covid-19, the disease caused by the virus. A study released this week on 368 male Veterans Affairs patients with the disease showed that the death rate among those given the drug, both in combination with another drug and alone, was higher than for those who were not. Researchers also said its use made no difference in the need for ventilators.

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For Fox News hosts, the hydroxychloroquine controversy is fuel for the culture war

Like other fast-moving research about covid-19 treatments, the study by VA and academic researchers hasn’t undergone the typical peer-review process and isn’t the kind of formal clinical trial, like those underway elsewhere, that will offer more definitive answers. However, it was based on one of the largest collections of data about the drug’s use.

Another study, released by French researchers last week, offered more discouraging clues. It found no statistically significant difference in the death rates among 181 covid-19 patients who had taken hydroxychloroquine within 48 hours of being admitted to a hospital and those who hadn’t. The study also highlighted dangerous side effects; eight developed arrhythmia, or abnormal heart rhythms, and had to stop taking it.

On Tuesday, an expert panel convened by the National Institute of Allergy and Infectious Diseases, advised physicians against prescribing hydroxychloroquine with the antibiotic azithromycin because of the potential side effects. The panel said there wasn’t enough evidence yet to recommend for or against hydroxychloroquine as a treatment. The agency is headed by Trump’s top infectious disease adviser, Anthony S. Fauci, who has repeatedly tempered Trump’s upbeat commentary about the drug.

All of which raises a question about the Fox News hosts’ advocacy of hydroxychloroquine: Were they pushing a potentially ineffective, even dangerous, remedy in the absence of sound science and well in excess of their expertise or knowledge?

A Fox spokeswoman declined to comment directly on any primetime commentary but mentioned recent segments that “show the network’s attention to all sides of this story from a news and opinion perspective.”

Carlson, Hannity and Ingraham didn’t mention the new research on their programs on Tuesday. The topic has faded from their commentary, replaced by rhetoric about China’s culpability for the pandemic and advocacy for reopening the country, again seemingly as part of a feedback loop with Trump’s own comments.

Ingraham, who met with Trump in early April to urge him to push the drug, hasn’t discussed hydroxychloroquine since April 15. She tweeted on Wednesday that she would address the new research about it on Wednesday. (She also tweeted, in reference to another pandemic-related topic, that “We made big decisions based on faulty data, bad models.”)

But syndicated TV host Dr. Mehmet Oz — an enthusiastic promoter of the drug in his many guest appearances on Fox News — seemed to backpedal from his usual advocacy on Wednesday’s “Fox and Friends.”

“The fact of the matter is, we don’t know,” he told co-host Brian Kilmeade, adding, “There’s a lot of variables. Brian, I gotta say at this point there is so much data coming from so many places, we are better off waiting for the randomized trials Dr. Fauci has been asking for. Otherwise, we keep reacting back and forth to studies that show opposite results, and a lot of it might have to do with when you get the medication.”

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Oz, a cardiac surgeon with limited expertise in pharmacology or virology, had previously said on Fox News that Fauci — the government’s leading infectious-disease expert — needed to “respect” the positive results of studies conducted to date, even if they were small.

Given the new data, Fox News has an obligation to give equal time to the doubts and potential dangers of hydroxychloroquine, said William Haseltine, the eminent biologist and biotech entrepreneur.

“That’s just public responsibility,” said Haseltine, who is chairman and president of Access Health International, a nonprofit organization that seeks to expand access to health care. “They have a duty to inform their [viewers] that they made a mistake. It’s not a crime to make a mistake, but they do need to correct it.”

In contrast to the network’s popular commentators, Fox’s News’s programs and website have been more cautious and have reported on the new research.

The network on Tuesday played clips from a White House press briefing in which Stephen Hahn, commissioner of the Food and Drug Administration, urged waiting for randomized clinical trials “to actually make a definitive decision around safety and efficacy.”

Trump sounded a bit less enthusiastic about hydroxychloroquine during the same briefing. He said he was unaware of the VA study. He also said, “Obviously, there have been some very good reports and perhaps this one is not a good report. But we’ll be looking at it.”