Marc Bernier was adamant: He was not going to get a coronavirus vaccination.

“I’m Mr. Anti-Vax,” he told listeners of his talk-radio program in Daytona Beach, Fla., after the federal government provisionally approved the first vaccines in December. He later declared that the government was “acting like Nazis” in urging people to get vaccinated.

But in early August, WNDB, Bernier’s radio home for more than 30 years, announced that the 65-year-old host was being treated in a hospital for covid-19. On Saturday, the station said that Bernier had died.

Bernier was at least the fourth talk-radio host who had espoused anti-vaccine and anti-mask sentiments to succumb to the virus in August. There was also Phil Valentine, 61, a popular host in Tennessee; Jimmy DeYoung, 81, a nationally syndicated Christian preacher also based in Tennessee; and Dick Farrel, 65, who had worked for stations in Miami and Palm Beach, Fla., as well as for the conservative Newsmax TV channel.

All four men had publicly couched their opposition to mainstream public health efforts in the typically hyperbolic and sometimes paranoid rhetoric of conservative talk radio. Farrel, for example, called coronavirus mitigation efforts “a scam-demic” and described the government’s top infectious-disease expert, Anthony S. Fauci, as “a power-tripping, lying freak.” At one point earlier this year, DeYoung, host of the “Prophecy Today” program, asked a guest whether the vaccine rollout could be “another form of government control of the people.”

Valentine’s sentiments took the form of a song parody — a format that had also been a favorite of the late talk-radio titan Rush Limbaugh. Valentine’s tune was called “Vaxman,” based on the Beatles’ “Taxman.”

Let me tell you how it will be.

And I don’t care if you agree,

‘Cause I’m the Vaxman.

Yeah, I’m the Vaxman.

If you don’t like me coming ’round

Be thankful I don’t hold you down . . .

Valentine released the song in June. He died on Aug. 21, according to his station, WTN in Nashville.

To some observers and critics, the hosts’ deaths highlighted talk radio’s often overlooked role as a vector of vaccine resistance and coronavirus misinformation. While several nationally syndicated hosts, such as Hugh Hewitt and Ben Shapiro, have spoken out to advocate for vaccines, hosts at hundreds of local stations have offered messages similar to those of Valentine, Farrel and Bernier.

“The vaccine isn’t the problem. Talk radio is,” said Jerry Del Colliano, a professor at New York University and publisher and editor of Inside Music Media, which covers the radio industry. Radio companies, he said, “are risking the health of their audiences even as anti-vaxxer bloviators continue to die.”

Del Colliano faulted lax oversight by the Federal Communications Commission and indifference by major radio station owners, such as iHeartRadio and Cumulus Media, the two largest talk-station companies.

Cumulus — which owns more than 400 stations in 80 cities, including the station that aired Valentine’s program — has mandated vaccination for all of its 4,000 employees; iHeart has no such mandate. The companies did not respond to requests for comment.

In the absence of vaccinations, the four hosts appear to have been particularly vulnerable to the coronavirus. All were older than 60, an age at which the risk of severe illness and death increases dramatically. All lived and worked in two states, Florida and Tennessee, that have been particularly hard hit by the highly contagious delta variant.

More broadly, the vaccine skepticism and outright defiance of public health mandates may have been baked into talk radio’s DNA ever since Limbaugh became a national force in the early 1990s, said Brian Rosenwald, a University of Pennsylvania scholar and the author of “Talk Radio’s America: How an Industry Took Over a Political Party That Took Over the United States.”

“Talk radio is inherently the outsider’s medium,” said Rosenwald, who also edits The Washington Post’s Made by History section. One common theme for hosts over the past three decades has been criticism of the mainstream media and the “liberal establishment,” consisting of the Democratic Party, Hollywood, universities and other perceived “elites,” he noted.

As such, the medium is “perfectly suited” to questioning the medical establishment and the use of government power, even when doing so might contradict scientific knowledge and undermine public health, he said. Even as he was receiving state-of-the-art care for cancer last year, Limbaugh maintained a skeptical, conspiratorial pose, falsely dismissing the then-emerging coronavirus as “the common cold” and saying, without evidence, that it was being “weaponized” to attack President Donald Trump.

Rosenwald said some of the rhetoric of conservative talk personalties is driven by a chicken-and-egg issue. That is, hosts tend to avoid getting on the opposite side of an issue from their listeners, lest they alienate them and harm their own ratings and the station’s bottom line. In this case, polls have shown skepticism and antipathy toward vaccines and mask mandates among self-identified Republicans, the core audience for talk radio. But it’s not known whether these attitudes have been shaped by talk radio (and like-minded politicians) or whether talk radio merely reflects and reinforces them, he said.

Away from the microphone, however, at least two of the deceased hosts expressed remorse for not urging people to get vaccinated.

In July, after Valentine was hospitalized for complications from covid-19, his brother Mark went on air and said on Valentine’s behalf: “For those listening, I know if he were able to tell you this, he would tell you, ‘Go get vaccinated. Quit worrying about the politics. Quit worrying about all the conspiracy theories.’ ”

His family later issued a statement indicating that Valentine had changed his mind about the vaccines he had mocked.

“Phil would like for his listeners to know that while he has never been an ‘anti-vaxer’ he regrets not being more vehemently ‘pro-vaccine,’ and looks forward to being able to more vigorously advocate that position as soon as he is back on the air, which we all hope will be soon,” the statement said.

Valentine never returned to the air.

Farrel also had a late-dawning change of heart, according to a longtime friend, Amy Leigh Hair.

“When he got very sick, he texted me and said, ‘This pandemic ain’t no joke. Get the shot,’ ” she said in an interview this week. “He definitely admitted he hadn’t taken it seriously. At the end of the day, he was sorry about that.”

Farrel died on Aug. 4, just a few days after his birthday.

“I know he changed his mind at the end,” said Hair. “I think Dick Farrel would be alive today if he had been vaccinated.”