Back in December, before the queen of England and the president-elect of the United States had their turns, the media mogul Rupert Murdoch received a dose of a Covid-19 vaccine. Afterward, he urged everyone else to get it, too.
Since then, a different message has been a repeated refrain on the prime-time shows hosted by Tucker Carlson and Laura Ingraham on Mr. Murdoch’s Fox News Channel — a message at odds with the recommendations of health experts, even as the virus’s Delta variant and other mutations fuel outbreaks in areas where vaccination rates are below the national average.
Mr. Carlson, Ms. Ingraham and guests on their programs have said on the air that the vaccines could be dangerous; that people are justified in refusing them; and that public authorities have overstepped in their attempts to deliver them.
Mr. Carlson and Ms. Ingraham last week criticized a plan by the Biden administration to increase vaccinations by having health care workers and volunteers go door to door to try to persuade the reluctant to get shots.
“Going door-to-door?” Ms. Ingraham said. “This is creepy stuff.”
Mr. Carlson, the highest-rated Fox News host, with an average of 2.9 million viewers, said the Biden plan was an attempt to “force people to take medicine they don’t want or need.” He called the initiative “the greatest scandal in my lifetime, by far.”
Mr. Carlson’s guest on that episode, the veteran Fox News political analyst Brit Hume, pushed back slightly, saying, “What they’re trying to do is make it as easy as possible for people to get the vaccine and, for people who are hesitant, to perhaps encourage them that they have nothing to fear.” Mr. Hume was quick to add that “vaccines do have side effects” and said those who are hesitant “should be respected.”
Served up to an audience that is more likely than the general population to be wary of Covid vaccines, the remarks by Mr. Carlson and Ms. Ingraham echoed a now-common conservative talking point — that the government-led effort to raise vaccination rates amounted to a violation of civil liberties and a waste of taxpayer dollars.
The comments by the Fox News hosts and their guests may have also helped cement vaccine skepticism in the conservative mainstream, even as the Biden administration’s campaign to inoculate the public is running into resistance in many parts of the country.
Public health experts have said that a strong vaccination effort is critical for the United States to outrun the virus, which has killed more than four million people worldwide and continues to mutate.
The amplification of vaccine skepticism through conservative media channels could harden the reluctance of those who might otherwise have been persuaded to get a shot, said Kathleen Hall Jamieson, a communications professor at the University of Pennsylvania.
“If you have constant exposure to an outlet that is raising vaccination hesitancy, raising questions about vaccinations, that is something to anchor you in your position that says, ‘I’m not going to take the vaccine,’” Ms. Jamieson said.
A Fox News spokeswoman provided past statements by Mr. Carlson voicing his general support for vaccines. “I’ve had a million vaccines in my life, as we all have,” the host said on an April show. “I think vaccines are great.” The spokeswoman also noted that Ms. Ingraham had spoken in favor of adults choosing to receive vaccines if they wanted them.
White House officials said on Thursday that virtually all new coronavirus hospitalizations and deaths nationwide involved unvaccinated people. The five states with the worst outbreaks as of Wednesday had below-average vaccination rates; four of them voted for President Donald J. Trump in the 2020 election.
Vaccine resistance was greater among Republicans than Democrats, according to an April study by the Public Religion Research Institute. Among Republicans who watch Fox News, 45 percent said they were hesitant or unwilling to get a Covid-19 shot, compared with 68 percent of viewers who watch the niche right-wing news channels Newsmax or One America News Network.
On his Wednesday program, Mr. Carlson went after colleges that have required students to be vaccinated before their return to campus.
“They shouldn’t get the shot,” said Mr. Carlson, who has not disclosed whether he is vaccinated against Covid-19. “It’s not good for them. There’s a risk involved, much higher than of Covid, but colleges are forcing them anyway.”
His guest for the segment, Charlie Kirk, a founder of the conservative group Turning Point USA, compared the campus precautions to “almost this apartheid-style open-air hostage situation, like: ‘Oh, you can have your freedom back if you get the jab.’”
Infections among younger people were a major factor in a surge last summer. When students returned to colleges last fall, there was another Covid spike. A new variant that spread rapidly in younger age groups filled hospital wards this spring. Health experts have said for months that Covid is far more dangerous than any potential risks associated with a vaccine.
During Mr. Carlson’s surge in popularity, major companies, including Disney, Papa John’s and Sandals, stopped buying ads on his show. In April, the Anti-Defamation League called on the host to resign after he mocked concerns about “white replacement theory,” which describes a racist conspiracy theory popular among right-wing extremists, and accused Democrats of “trying to replace the current electorate” with people he described as “new people, more obedient voters, from the third world.”
The host has had the unshakable support of his bosses. In a May interview with Insider, Lachlan Murdoch, the elder son of Rupert, who runs Fox News with his father, defended Mr. Carlson against his critics and called him “brave.”
As of July 4, 67 percent of American adults had received at least one shot, just short of President Biden’s goal of 70 percent. Media campaigns to increase vaccination rates, such as public service announcements from the nonprofit Ad Council, have been addressed to hesitant Americans.
While two of Fox News’s prominent hosts and their guests have questioned vaccination efforts, the channel has also produced its own vaccine P.S.A., a 30-second spot featuring the hosts and anchors Steve Doocy, Harris Faulkner, Dana Perino and John Roberts. “If you can, get the vaccine,” Ms. Faulkner says in the ad.
Bret Baier, the chief political anchor of Fox News, said in an Instagram post that he was “grateful” for the shot. In May, the hosts of “Fox & Friends” spoke on-air of their “relief” at getting vaccinated. And Ms. Faulkner hosted a prime-time special in February that sought in part to “debunk common myths” about the vaccine.
The prime-time Fox News host Sean Hannity, who fell behind Mr. Carlson in the ratings race during the Trump years, said on a May episode of “Hannity” that he planned to get a Covid-19 shot. “I do believe in science, and I believe in vaccinations,” he said.
“Talk to your doctor,” he continued. “You don’t need to talk to people on TV and radio that aren’t doctors.”
Ms. Ingraham has been more skeptical. Last week she accused the news media of overhyping the threat of Covid-19 to children and often refusing to discuss adverse reactions linked to the vaccines, although such outcomes have been covered by The New York Times, The Washington Post, CNN and other outlets.
“Despite everything the experts either got wrong or lied about, they still think that parents should trust them and inject their kids with an experimental drug to prevent a disease almost none of those kids will ever get sick from,” she said on her show. Ms. Ingraham has not revealed whether she has received a Covid vaccine.
While children are less likely to develop severe illness from Covid-19, data from the American Academy of Pediatrics showed that more than four million children had tested positive for the coronavirus since the pandemic began, that more than 16,500 had been hospitalized and that more than 300 had died in the United States.
Fox News is not the only outlet that has been critical of vaccine efforts. Newsmax covered Mr. Biden’s outreach plan on its website with the headline “Biden Blasted for ‘Sick’ Door-to-Door Vaccine Campaign”; One America News Network greeted the proposal with the headline “Joe Biden To Send Operatives To Harass Americans Into Taking COVID-19 Vaccines.”
Dr. Joshua M. Sharfstein, a public health professor at Johns Hopkins, called the rhetoric against vaccine campaigns “a terrible development.”
“We have such strong political opinions in this country,” he said, “and if people associate their political identity with a position on a public intervention, it’s very hard to penetrate that with good information.”
The remarks against vaccination efforts on “Tucker Carlson Tonight” and “The Ingraham Angle” have come during a ratings resurgence for Fox News.
For years, Mr. Murdoch’s channel was the ratings leader among cable news networks — only to fall behind CNN in the wake of the 2020 election, when Fox News was the first news organization to project Mr. Biden as the winner of Arizona, a key swing state.
Newsmax, which was more frankly pro-Trump in its coverage, gained viewers in the weeks after Election Day. At the same time, One America News accused Fox News of joining “the mainstream media” in an effort to recruit the channel’s disaffected fans.
Now the old ratings order has been restored: Fox News finished far ahead of its main rivals, CNN and MSNBC, with an average of nearly 2.2 million viewers during prime time in the second quarter of 2021, according to Nielsen.
Its return to the top came thanks, in part, to a programming strategy that gave more hours per week to opinion shows, rather than news broadcasts. And as it climbed back to ratings dominance, the commentator Donna Brazile, a former Democratic Party chairwoman, departed the network, and Juan Williams, a moderate pundit, left his role as a co-host of “The Five.” Both had served as foils to the channel’s conservative voices.
In a recent opinion essay for The Daily Beast, Preston Padden, a former high-level executive at Fox Broadcasting, wrote that Fox News had “contributed substantially and directly” to “the unnecessary deaths of many Americans by fueling hesitation and doubt about the efficacy and safety of lifesaving Covid-19 vaccines.” He singled out the channel’s prime-time opinion programs for blame.