As the Centers for Disease Control and Prevention urged vaccinated people to resume wearing masks under certain circumstances amid low vaccination rates and rising cases from the delta variant, Fox News host Tucker Carlson placed blame on Anthony S. Fauci for the changing mask guidelines.

In doing so, Carlson on Wednesday night falsely claimed that the nation’s top infectious-disease expert had caused the coronavirus.

“Here’s the man who helped to create covid in the first place,” Carlson said.

The host doubled down on the baseless claim minutes later on “Tucker Carlson Tonight” when he cited a handful of “breakthrough” cases of vaccinated people still getting infected by the virus. Studies have shown the two-dose coronavirus vaccines from Pfizer and Moderna are about 95 percent effective at preventing infection, while Johnson & Johnson’s one-shot vaccine is 72 percent effective.

“They have been telling us for six months that this vaccine is perfect, but clearly, in some cases, it doesn’t always work,” Carlson said. “And that’s not our theory, by the way. Take it from the guy who created covid.”

The origin of the coronavirus, which has infected more than 196 million people worldwide and killed nearly 4.2 million, remains unknown. Public-health scientists in 2020 signed a letter to the Lancet saying that the coronavirus was not a bioengineered virus and condemning “conspiracy theories suggesting that covid-19 does not have a natural origin.” President Biden asked U.S. intelligence agencies in May to “redouble their efforts” to determine the origin of the coronavirus — an abrupt departure from the previous White House position of relying on the World Health Organization to uncover how the contagion started.

Carlson’s false claim regarding Fauci comes after federal health officials warned this week that even people who are vaccinated and become infected with the highly transmissible delta variant can harbor large amounts of coronavirus just like unvaccinated people. The changed guidance, which recommends masking in high-transmission areas and calls for universal masking for teachers, staff members and students in schools, comes as confirmed coronavirus infections nationwide have quadrupled in July. The number of coronavirus cases this month went from about 13,000 cases per day on average at the start of the month to more than 56,000 toward the end of the month, according to data compiled by The Washington Post.

Top health officials Anthony S. Fauci and Rochelle Walensky said July 28 that vaccinated individuals should wear masks indoors, per new CDC guidance. (The Washington Post)

Some outside scientists are pushing for the CDC to show the public the data from outbreak investigations in which researchers compared delta infections among vaccinated and unvaccinated people. In an interview this week with The Washington Post, Fauci noted while there is not yet clinical data on what the high viral loads mean in terms of disease transmission, “you can make a reasonable assumption that vaccinated people can transmit the virus just like unvaccinated people can.”

“I think the implications [of the data] are that people who are vaccinated, even when they’re asymptomatic, can transmit the virus, which is the scientific foundation of why this recommendation is being made,” said Fauci, Biden’s chief medical adviser.

Representatives with Fox News did not respond to a request for comment Thursday. Neither Fauci nor spokespeople with the White House responded to messages left for them.

Carlson, who has described himself as “pretty pro-vaccine,” has regularly challenged the efficacy of vaccination against the coronavirus to his millions of viewers on his prime-time show. “Maybe it doesn’t work, and they’re simply not telling you that,” he said in April. The claim caused Fauci to rebut what he deemed a “crazy conspiracy theory.”

Fauci and the Biden White House have spoken repeatedly about how misinformation surrounding the vaccine has led to not just hesitancy but also hostility from those who remain unvaccinated. Though Fox News host Sean Hannity made headlines when he recently urged viewers to “please take covid seriously,” The Post’s Philip Bump noted that Hannity’s limited endorsement of vaccine was still “a small drop in Fox News’s ocean of doubt.”

When asked by CNN’s Jim Acosta this month about how Carlson’s hostility toward the vaccine would have looked when the country was fighting polio or the measles, Fauci wondered what damage the pushback could have caused.

“If we had the pushback for vaccines the way we’re seeing on certain media, I don’t think it would’ve been possible at all to not only eradicate smallpox. We’d probably still have smallpox, and we’d probably still have polio in this country if we had the kind of false information that’s being spread now,” he said. “If we had that back decades ago, I’d be certain we’d still have polio in this country.”

On Wednesday, Carlson again focused his attention on Fauci and whether he and the National Institutes of Health funded gain-of-function research in the Wuhan Institute of Virology. Some Republicans, including former president Donald Trump, have pushed the idea that the Wuhan lab, rather than a natural transmission from animals to humans, was at fault for the virus.

Fauci told Sen. Rand Paul (R-Ky.) during a Senate hearing in May that he was “entirely and completely incorrect that the NIH has not, never and does not now fund gain-of-function research in the Wuhan Institute of Virology.” Gain-of-function research is basic biological studies deemed by some as potentially dangerous for allowing scientists to study how to combat future viruses. As The Post’s Fact Checker noted, “the NIH connection to possible gain-of-function research appears so far to be elusive.”

Sen. Rand Paul (R-Ky.) and infectious-disease expert Anthony S. Fauci clashed over Wuhan lab funding during a Senate hearing on July 20. (The Washington Post)

Despite the new CDC guidance, Carlson claimed without evidence that the new guidelines came from lawmakers trying to hold on to the “unprecedented levels of power” they have amassed in the past year.

“They’re going to keep ordering you around, regardless of the science,” Carlson said on his show. “And, of course, Tony Fauci is going to do his best to defend it all.”

Fauci has reiterated that the state of coronavirus in the United States has significantly altered since May 13, the date the CDC said that vaccinated people did not need to wear masks indoors or outside because of the protection afforded by the vaccines.

“The situation has clearly changed,” he recently told The Post.

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