Ron DeSantis wrong that boosters make COVID-19 infection more likely

HAMPTON, N.H. — During his presidential campaign, Florida Gov. Ron DeSantis has emphasized the speed with which he opened his state during the coronavirus pandemic. He argued this move unleashed the economy when many other states were struggling because of pandemic-related shutdowns.

After initially supporting the coronavirus vaccine during its wide rollout in early 2021, DeSantis and his allies have expressed skepticism about them. DeSantis’ hand-picked state surgeon general, Joseph Ladapo, for example, argued that small DNA fragments in the vaccines could pose a "unique and elevated risk to human health." PolitiFact found the scientific consensus says they don’t.

During a visit to this Atlantic Ocean beach town, more than 100 supporters packed into Wally’s restaurant to hear DeSantis speak and take questions.

DeSantis urged caution about the coronavirus vaccine that medical officials and most doctors still urge Americans to get. He said people who get the vaccine are likelier to get sick.

"Every booster you take, you’re more likely to get COVID as a result of it," DeSantis said.

DeSantis said something similar in January 2023: "Almost every study now has said with these new boosters, you're more likely to get infected with the bivalent booster." We rated that False.

For this article, we checked back with experts to whether any developments changed their assessment during the subsequent year. All disagreed with DeSantis.

Neither the DeSantis campaign nor his gubernatorial office responded to an inquiry for this report.

Broadly speaking, COVID-19 vaccines are not designed to prevent infection; they prevent the virus from spreading within the body and causing severe illness.

"COVID-19 vaccines, including boosters, have now been shown to be most effective against severe disease," said Monica Gandhi, a professor of medicine and associate chief in the division of HIV, infectious diseases, and global medicine at the University of California, San Francisco.

Gandhi said the most recent boosters were tailored to target one variant, XBB1.5. She said the boosters have been shown to significantly reduce COVID-19 hospitalizations in people older than 65, including in a recent study from Denmark. 

DeSantis’ comments hint that he is holding the vaccine to a standard — complete protection against infection — that it was never intended to provide.

One study DeSantis’ office cited for our story a year ago came from the Cleveland Clinic and was discussed in an opinion article in The Wall Street Journal. 

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But Dr. Nabin Shrestha, an infectious disease physician and one of the study's authors, told PolitiFact at the time that, contrary to DeSantis’ remark, the data did not find a link between getting the shot and having a higher risk of contracting COVID-19. 

What drove coverage in outlets such as The Wall Street Journal was an "unexpected" association researchers found between the number of prior vaccine doses and an increased risk of contracting COVID-19. People with three or more doses of the vaccine had a higher chance of getting infected. 

However, experts told PolitiFact that the study population was not reflective of the general public; it consisted of younger, relatively healthy health care workers and included no children and few elderly or immunocompromised people. Therefore, experts said, the study cannot simply be extrapolated to the population at large.

René Najera, an epidemiologist and director of the Center for Public Health at the College of Physicians of Philadelphia, told PolitiFact last year that the population tested would be "more likely to be exposed and more likely to be vaccinated as well. … The findings would only be applicable to health care workers in large settings such as the Cleveland Clinic, not the general public."

Gandhi and other medical professionals told PolitiFact that studies like the Cleveland Clinic’s are imperfect, because it is hard to conduct real-world experiments that gauge infection rates, especially for vulnerable populations. Studies tend to get participants who are healthy and are likelier to get boosters, Gandhi said.

Therefore, studies of this sort are "subject to massive bias," said Babak Javid, associate director of bench science at the University of California-San Francisco Center for Tuberculosis Medicine. 

Javid says there’s also significant overlap among the people who get the new booster and those who test themselves frequently. "Since infection status can only be documented if a test is performed, it could easily explain how more vaccinated people are in the 'infected' camp," he said. People who are not getting vaccinated or tested simply won’t be counted, skewing attempts at making comparisons.

Another complication in tracking infection rates is that coronavirus vaccines present the same dynamics as any vaccine. That is, by protecting against one strain, or just a few strains, of a given virus, vaccinated people are still liable to get infected by a different strain that the vaccine doesn’t cover, said Jill Roberts, an associate professor in the College of Public Health, Global and Planetary Health at the University of South Florida.

That’s why many vaccines, such as flu and COVID-19 shots, need frequent updating, experts said. 

Gandhi said that although the boosters have long been known to offer only "modest protection, if at all, against COVID-19 infection ... there is no evidence to suggest that boosters actually increase the risk of COVID-19 infection."

Thus, she said, DeSantis "is incorrect in saying boosters will lead to more frequent infections."

DeSantis said, "Every booster you take, you’re more likely to get COVID as a result of it."

Experts say there is no hard evidence that infection is greater in people who have had boosters.

Part of the reason is that determining infection rates among all members of society is difficult. Most studies rely on younger and healthier patients, who are not necessarily typical. Also, people who are not getting vaccinated or tested simply won’t be counted, skewing attempts at comparisons, experts said.

We rate the statement False.