CLAIM: A study published in The Lancet proves that COVID-19 mRNA vaccines increase people’s chances of contracting the disease after seven months, providing further evidence that people should not get vaccinated.
AP’S ASSESSMENT: Misleading. The observational study out of Qatar found that people who received a booster shot with the original vaccine formulation had overall lower rates of infection than those with only two doses over the course of a year. It also found those who were boosted were 75% less likely to experience severe COVID-19. The report did find higher infection rates among the boosted specifically after seven months, but outside experts said the study doesn’t prove the vaccines are biologically increasing recipients’ risk of infection.
THE FACTS: Florida’s Surgeon General Joseph Ladapo cited the study Thursday while suggesting that no one should be receiving the widely used mRNA shots.
It was the latest in a continuing campaign against public health measures fighting the coronavirus: U.S. health agencies recently sent Ladapo a letter warning him that his claims about vaccine risks are harmful to the public.
While speaking at a press conference with Republican Gov. Ron DeSantis, who appointed Ladapo in 2021, the surgeon general claimed that the mRNA vaccines “have a terrible safety profile” and said he was “not sure anyone should be taking them” anymore.
He went on to say the study in The Lancet showed protection from infection around 70% plummeting within seven months to “the other side of the axis, right, so it is negative and that continues.”
“And the magnitude of that negativity increases over time,” Ladapo continued. “What does that mean, folks? It literally means that the people who received that vaccine were more likely to contract COVID-19 after seven months than the people who did not. That is a fact.”
Nikki Whiting, a Florida Health Department spokesperson, said Ladapo’s point was that most people have some existing immunity from COVID-19 from a prior infection and that the study’s finding concerning negative immunity months later means that “risk of infection is higher.”
But lead study author Hiam Chemaitelly, a researcher at Weill Cornell Medicine – Qatar, said in an email that Ladapo’s remarks were “a mischaracterization of our findings.”
The study did not compare people who were vaccinated versus those who were unvaccinated, Chemaitelly said, as Ladapo’s comments may have suggested. She said her study showed that booster doses “remain essential, particularly for the elderly and those with comorbidities to protect them against severe COVID-19.”
The researchers found that individuals who received a booster shot “were 75% less likely to experience severe COVID-19 compared to those who remained with only the two-dose primary series,” Chemaitelly said. The study looked at boosters using the old formulation, not the newer, omicron-targeting booster shots that better match the strain of the virus now circulating.
During the overall year-long follow-up period, those who received a booster dose tested positive for COVID-19 less than people with only two doses.
But there was a caveat: After month seven, those who received the booster shot had a higher incidence of infection than those with only two doses — the finding that Lapado homed in on.
The authors suggested that the finding may be due to a biological phenomenon. In short, they theorized that the increased infection totals among the boosted may be because their immune systems attempted to fight new variants by targeting the old form of the virus used in the original vaccines.
While the study’s authors stood by their theory, four independent experts told the AP they believe the study can’t reliably draw such conclusions because of its inability to control for different factors.
The study was observational, meaning it relied on existing data about vaccinations and testing to compare the groups of people who received two doses and three doses.
“You have to make sure those two groups are alike in all other aspects so that the only variable between those two groups is the receipt of a booster dose,” said Dr. Paul Offit, a national vaccine expert at the Children’s Hospital of Philadelphia, otherwise the results may be skewed.
Those who seek out a third or fourth dose may be more vulnerable — elderly or immunocompromised, for example. “You’re likely selecting for a group that may be more likely to get sick,” Offit added.
Matt Hitchings, an infectious disease epidemiologist and professor of biostatistics at the University of Florida, said the group behind the study “has done a lot to enhance our understanding of vaccine effectiveness” but said they did not prove that a biological increased infection risk was actually occurring.
“I do think, in this case, that they have not done enough to be clear about other possible explanations for the pattern that they’re seeing,” he added.
Dr. Otto Yang, a professor of medicine, microbiology, immunology and molecular genetics at the University of California, Los Angeles, similarly pointed out the biases of such studies.
“There are reasons why certain people would be boosted or not boosted, and how often they get tested…and those factors certainly will affect how much risk for infection they face, and how efficiently an asymptomatic or mildly symptomatic infection would be diagnosed or not diagnosed,” he said.
Spencer Fox, an assistant professor of epidemiology and biostatistics at the University of Georgia, said in an email: “The negative effectiveness following initial immunity could be caused by many other factors, including behavioral differences between the populations (e.g. if people with 3 vaccines acted riskier because of their perceived protection).”
The focus on the infection rates misses the point that the vaccines’ most important feature is their ability to help protect people from getting seriously ill or dying, Offit said, which has been proven repeatedly. Asymptomatic and mild infections will continue to occur regardless because the virus is not going away.
“The notion that we don’t need to give vaccines anymore is irresponsible and ill-founded,” he added.