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Clinical trials and real-world studies have shown the available COVID-19 vaccines to be effective at protecting against COVID-19 infections and severe symptoms.
Responding to Fox News host Tucker Carlson’s suggestion that the vaccines might not work, Dr. Anthony Fauci said the clinical trials showed "an overwhelming signal of efficacy."
The CDC still recommends that fully vaccinated people wear masks and keep their distance in public spaces. There are legitimate reasons for that, experts said, including the fact that many Americans have not yet been vaccinated.
In a comment that Dr. Anthony Fauci, the nation’s top infectious disease expert, rejected as a "crazy conspiracy theory," Fox News host Tucker Carlson suggested to his millions of viewers that the COVID-19 vaccines might not work.
Clinical trials and real-world studies have shown the available vaccines are effective at protecting against COVID-19 infections and severe symptoms, despite Carlson’s claim.
The Fox News host opened his April 13 segment by talking about the recent recommendation by federal regulatory agencies to pause use of the Johnson & Johnson vaccine, one of three vaccines approved for emergency use in the U.S. The agencies are investigating six reports of a rare but severe type of blood clot among the more than 6.8 million people who got the shot.
Carlson then turned to the Centers for Disease Control and Prevention’s latest public health guidance advising fully vaccinated Americans to continue taking precautions in public spaces.
"If the vaccine is effective, there is no reason for people who've received a vaccine to wear masks or avoid physical contact," he said. "So maybe it doesn't work, and they're simply not telling you that. Well, you'd hate to think that, especially if you've gotten two shots. But what's the other potential explanation? We can't think of one."
Carlson’s primetime show is among the most-watched cable news programs, and a video of his April 13 segment received nearly one million views on Facebook.
The video was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)
Asked about Carlson’s comments, Fauci told CNN that they were "certainly not helpful to the public health of this nation."
"That’s just a typical crazy conspiracy theory," Fauci said. "Why would we not tell people if it doesn't work? Look at the data. The data are overwhelming in the three vaccines that have been approved for use in an emergency use authorization, the J&J, the Pfizer, and the Moderna. You had 30,000, 44,000, and 40,000 people in the clinical trials, with an overwhelming signal of efficacy. So I don’t have any idea what he’s talking about."
The proof that the vaccines work includes a lengthy regulatory process and vaccine trials that happened around the world.
The Food and Drug Administration has authorized for emergency use two-dose vaccines from Pfizer-BioNTech and Moderna, as well as a one single-dose vaccine from Johnson & Johnson. The three were approved after clinical trials involving tens of thousands of participants.
As of April 15, nearly 126 million Americans had received at least one dose of a vaccine, and over 78 million have been fully vaccinated, according to the CDC. The Pfizer and Moderna vaccines have accounted for the vast majority of those inoculations.
Clinical trials showed the Pfizer vaccine to be 95% effective at preventing COVID-19 infections, compared with 94% for Moderna and 66% for Johnson & Johnson, according to the CDC. The Johnson & Johnson vaccine was also found to be 85% protective against severe disease.
The clinical trials "clearly show the efficacy of each vaccine," said Richard Watanabe, professor of preventive medicine at the University of Southern California.
Some fully vaccinated people can still get infected, since no vaccine is 100% effective. But the clinical studies show the vaccine can keep them from getting seriously ill, the CDC says.
"It is incontrovertible that the vaccines work," said Amesh Adalja, a senior scholar at the Johns Hopkins Center for Health Security. "Just look at hospitalization rates."
Further studies have since supported the trial findings. A CDC study published March 29 found that under "real-world conditions," the Pfizer and Moderna vaccines were 90% effective against infections two weeks after the second dose and 80% effective 14 days after the first dose.
A separate study conducted in Israel and published Feb. 24 in the New England Journal of Medicine found that two doses of the Pfizer vaccine provided nearly 90% protection.
"Israel is a good example of what high population-level vaccination rates can achieve," said Brooke Nichols, assistant professor of global health at Boston University. "Once they achieved high vaccination coverage, cases began to plummet."
Carlson’s claim that "maybe (the COVID-19 vaccine) doesn’t work" hinged on the CDC’s latest guidance recommending that fully vaccinated Americans continue taking precautions in public.
Carlson said there are no good reasons for that. We found several, though.
The guidance reflects the fact that scientists are still learning about the vaccines: how long protection lasts; how much vaccines protect against emerging variants of the virus; and to what extent the vaccines prevent asymptomatic infections and transmission of the virus.
The CDC says preliminary evidence indicates that the vaccines "may provide some protection" against certain variants, and that "a growing body of evidence" suggests fully vaccinated people are less likely to be asymptomatic carriers of the virus and potentially less likely to pass it along to others.
But the science on those questions is not settled, Watanabe said, and fears that newer variants could be more transmissible make additional safeguards important for now.
In public spaces, there is no way to tell who is among the roughly 25% of the U.S. population that has been fully vaccinated. Some "very vulnerable people" remain at risk, Nichols said.
"Public health guidance on masks is not going to change until enough people are vaccinated because it is operationally very difficult to be able to tell who was vaccinated and who is not if you are, for example, working in a store," Adalja said.
Responding to Fauci’s criticism on his show April 14, Carlson claimed he had "never for a minute doubted" that the COVID-19 vaccines work, despite expressing that very doubt the night before, and saying there was no other plausible explanation for the CDC’s guidance
"Who is doubting that vaccines work? For the record, we never for a minute doubted it. We bought all of that stuff completely at face value. We believe in science," Carlson said, adding that he trusted the pharmaceutical companies behind the vaccines. "The only reason we are asking the question is because the people in charge are acting like it doesn't work."
A Fox News spokesperson cited those comments and other examples of Carlson claiming to support vaccines, including when he said he’s "not against it on principle" during his April 13 segment and when he said March 30, "I think of myself as pretty pro-vaccine myself."
On Feb. 9, Carlson said the government’s handling of the vaccines "did not inspire confidence" and that U.S. authorities were "lying" about their safety and effectiveness. On other occasions, he has suggested that the government is using the vaccines as a form of "social control" and that the shots would be made mandatory, which is not the case.
Many questions about the vaccines that Carlson has claimed authorities have "discouraged" Americans from asking have been answered by public health agencies and also by news outlets, including PolitiFact.
Carlson said, "Maybe (the COVID-19 vaccine) doesn't work, and they're simply not telling you that."
That claim is countered by clinical trials and real-world studies that show the available vaccines effectively protect against COVID-19 infections and severe symptoms.
Carlson based his claim largely on the fact that the CDC still recommends that fully vaccinated people wear masks and keep their distance in public spaces. Carlson said he couldn’t think of a reason why the CDC would do that, but we found some pretty simple explanations.
Experts said those precautions are advisable because most of the U.S. population remains unprotected and because scientists are still studying to what extent the vaccines stop transmission, among other things.
We rate Carlson’s statement Pants on Fire!
Fox News, "Tucker Carlson Tonight," April 13, 2021
Fox News, "Tucker Carlson Tonight," April 14, 2021
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Statement from Fox News, April 14, 2021
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Email interview with Amesh Adalja, senior scholar at the Johns Hopkins University Center for Health Security, April 14, 2021
Email correspondence with Drew Weissman, professor of medicine at the University of Pennsylvania Perelman School of Medicine, April 14, 2021
Email interview with Richard Watanabe, professor of preventive medicine and associate dean for health and population science programs at the University of Southern California’s Keck School of Medicine, April 14, 2021
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