Este artículo estará disponible en español en El Tiempo Latino.
An abundance of evidence indicates the mRNA COVID-19 vaccines are remarkably safe and work well to protect against severe disease. But last month, the state of Florida issued updated vaccine guidance advising “against the use” of the shots entirely — even for people who are older and at higher risk of severe disease. Experts say the advice is ill-informed and “illogical.”
In late August, in time for the fall season, the Food and Drug Administration authorized and approved updated COVID-19 vaccines that target JN.1-lineage omicron variants of the coronavirus, or SARS-CoV-2. The options include the mRNA vaccines from Pfizer/BioNTech and Moderna — the vaccines that the vast majority of Americans have received in the past — and a protein subunit vaccine from Novavax for those 12 years of age and older.
The Centers for Disease Control and Prevention advises that everyone over the age of 6 months get an updated vaccine, noting that vaccination is most important for higher-risk people, including those who are pregnant, older or have certain medical conditions. (For more, see “Q&A on the 2024-2025 COVID-19 Vaccines.”)
Several weeks after the new vaccines became available, however, the Florida Department of Health issued a bulletin that directly contradicted both agencies’ determinations. Citing alleged safety concerns and claiming that the vaccines are both unnecessary and unlikely to work against the circulating variants, the bulletin said that “the State Surgeon General advises against the use of mRNA COVID-19 vaccines.”
Without explicitly naming the alternative — Novavax — the Sept. 12 guidance appeared to reluctantly endorse that vaccine for higher-risk people.
“Any provider concerned about the health risks associated with COVID-19 for patients over the age of 65 or with underlying health conditions should prioritize patient access to non-mRNA COVID-19 vaccines and treatment,” it read.
Experts, however, say there’s no rationale for advising against the mRNA vaccines.
“That’s silly,” University of Arizona immunologist Deepta Bhattacharya said of the guidance in an interview. “It doesn’t seem to be evidence-based at all.”
“The strength of evidence for booster effectiveness may be weaker than that for the original primary series vaccination, but well designed studies have consistently shown booster effectiveness against severe disease, and that boosters generate an updated immune response,” Matt Hitchings, an assistant professor of biostatistics who studies vaccine effectiveness at the University of Florida, told us in an email. He added that he was unaware of any clear evidence that the risks outweigh the benefits.
Indeed, while Florida’s guidance purported to be informing the public about issues the federal government has ignored, the studies it linked to are often cherry-picked, problematic or misinterpreted.
One issue the bulletin raised, for example, is the idea that the mRNA vaccines are potentially dangerous because they might insert genetic material into a person’s DNA. To make this claim, the bulletin cited an unpublished and widely criticized report that alleged DNA contamination in the mRNA vaccines. But as we’ve written, there’s no credible evidence the vaccines have excessive amounts of residual DNA, which is expected in trace amounts, or that it can integrate into a person’s genome. Moreover, all vaccines made from cells — like the Novavax vaccine — have residual DNA and there is no indication it is harmful.
“It’s so poorly reasoned, it’s hard to watch. It’s like science denialism by scientists,” Dr. Paul A. Offit, a vaccine expert at the Children’s Hospital of Philadelphia, told us, noting that Florida’s surgeon general, Dr. Joseph Ladapo, has an M.D. and Ph.D. from Harvard. “There’s just no excuse for this kind of behavior.”
A controversial figure who has repeatedly issued vaccine guidance in opposition to public health experts and organizations, Ladapo was appointed by Gov. Ron DeSantis in 2021. We and others have repeatedly fact-checked his claims, which often distort scientific findings or play up dubious ones.
Over time, Ladapo has suggested or advised more and more Floridians not to get an mRNA COVID-19 vaccine — first, just children, then young males, then all people under 65.
In January, Ladapo called for a “halt” in the use of the mRNA vaccines entirely, citing unsubstantiated concerns about DNA contamination. The latest guidance extended that prohibitory recommendation to everyone but specifically addressed the updated vaccines for the 2024-2025 season.
Bulletin Misunderstands Vaccine Evaluation and Updating Processes
Two major thrusts of the Sunshine State’s bulletin were the misleading claims that the updated vaccines were not tested properly and don’t work against the latest variants.
“The most recent booster approval was granted in the absence of booster-specific clinical trial data performed in humans,” the bulletin read, adding that the updated vaccines do “not protect against the currently dominant strain.”
“Although randomized clinical trials are normally used to approve therapeutics, the federal government has not required COVID-19 vaccine manufacturers to demonstrate their boosters prevent hospitalizations or death from COVID-19 illness,” the bulletin continued.
It’s true that the updated vaccines were not tested in people (the original COVID-19 vaccines, of course, were tested in very large randomized controlled trials). But as we’ve explained before, this is neither unusual nor a problem. Because the change to the COVID-19 vaccines for this year is so small — and previous versions of the vaccines have been exceptionally well studied, showing their safety and ability to protect against severe disease — regulators specifically do not require clinical testing, just as they don’t require such testing with seasonal influenza vaccines, which also need to be updated each year.
“This is the most tested vaccine in human history,” Offit said. “We have a wealth of data because so many people have been vaccinated.”
It’s also true that the updated vaccines are not an exact match for what is currently circulating — but it’s incorrect to claim that that means they offer little or no protection. Closer matches should offer better protection, including some ability to reduce infection, but even a fairly distant match will still reduce the risk of severe disease, which is the main goal of vaccination.
“They’re never a perfect match because the vaccine strain choices made back in June, and while the vaccine doesn’t change the virus keeps replicating and the virus keeps mutating,” Andrew Pekosz, a virologist at Johns Hopkins University, said in a briefing for reporters. But for the most part, he added, this year’s vaccines do appear to be a good match to what’s out there.
The Novavax vaccine targets the JN.1 omicron variant, while both mRNA vaccines target KP.2, a slightly more current JN.1-lineage variant. Neither variant is still circulating much, but the major variants today are highly related to these variants. Unless there is a major shift, the updated vaccines are expected to provide good protection against severe illness.
“Boosters have generally been shown to have significant protection against severe disease, hospitalization, and death, and there’s no particular reason to think it would be any different with the latest updated vaccines,” Hitchings said. “Antibodies generated to closely related strains will provide cross-protection, and we have seen that individuals with more vaccinations and/or infections have a ‘broader’ antibody response.”
“There are some parts of the virus that are not changing and those are still sites of vulnerability for the virus,” Bhattacharya also explained. “You’re still making a ton of protective antibodies.”
Misleading Safety Concerns
The bulletin went on to highlight various alleged health concerns of the vaccines, many of which are unproven, unfounded or lack important context.
For example, citing a 2022 paper published in Nature Cardiovascular Research, the bulletin noted the mRNA COVID-19 vaccines “may be associated with an increased risk” of an autonomic nervous system disorder known as postural orthostatic tachycardia syndrome, or POTS. Patients with this condition get dizzy when standing and often experience fatigue and brain fog, among other symptoms.
The cited paper did identify “a possible association” between POTS and COVID-19 vaccination. But it also noted that the increased odds of POTS following vaccination in the study were “lower than the odds of new POTS diagnosis after SARS-CoV-2 infection” — a key detail the bulletin left out.
“These study results are not intended to discourage use of the COVID-19 vaccine, especially given the relatively higher risk of developing POTS after SARS-CoV-2 infection,” the authors wrote in a research briefing published along with their paper.
POTS is known to be triggered by other infections. A surge of cases has occurred with the pandemic and POTS-like symptoms are common among people with long COVID.
The Florida bulletin also claimed an “increased risk of autoimmune disease after vaccination.” But experts said there isn’t clear evidence of an increased risk.
“Sometimes you can find these small risks in these epidemiological studies, and whether or not that’s real … can be pretty hard” to tell, Bhattacharya said. “What you’re looking for is, has this finding been found over and over again in these large studies? And the answer is no.”
The bulletin linked to a large South Korean study, published in Nature Communications in July, that found compared with a historical control group, mRNA vaccination was associated with a 16% increased risk of lupus after one year. It also found booster vaccination was associated with small increases in risk for alopecia areata, psoriasis and rheumatoid arthritis. The overall conclusion, however, was that mRNA vaccinations “are not associated with an increased risk” of most autoimmune diseases.
The authors called for additional monitoring, but said their results were “not sufficient to discourage booster vaccination” and that the linkage to lupus “remains unclear.”
Hitchings told us the data on autoimmune diseases and vaccination is “very mixed,” but what is clear is that coronavirus infection “is associated with increased risk of new onset autoimmune disease, and that COVID-19 vaccination protects against this.”
Numerous studies, including large ones in the U.S., Germany, Hong Kong, and South Korea and Japan, have identified such associations, with several indicating that vaccination helps reduce the risk.
Finally, the bulletin claimed that mRNA or spike protein from the vaccine sticks around too long and “may carry health risks.” But there is little evidence that this on its own — if or when it occurs — is harmful.
One of the studies cited for this is a 2022 Cell paper, which found in people that vaccine “spike antigen and mRNA persist for weeks” in specialized structures in the lymph nodes. But this is likely good — not bad.
Stanford immunologist and senior author Dr. Scott Boyd explained on X when the paper was first published that finding spike protein “in the lymph nodes of vaccine recipients gives some evidence for why the vaccines are working well. Lymph nodes are the desired destination for vaccine antigens, because that is where antibody producing responses are organized.”
“Finding some vaccine RNA in lymph nodes may help to explain why the viral spike protein is present there for longer times,” he added. “We don’t have any evidence that this is a harmful event.”
The paper the bulletin linked to for carrying a “health risk” related to this concern was about myocarditis. Myocarditis and pericarditis, or inflammation of the heart muscle or its surrounding tissue, respectively, are the main serious side effects of the COVID-19 vaccines (including the Novavax vaccine).
The conditions, however, are rare and primarily affect young males after a second dose. Moreover, the CDC and FDA are aware of these risks, continue to monitor for them and have determined the benefits outweigh the risks.
The cited paper, a study published in Circulation in 2023, found free spike protein in the blood of people with vaccine-related myocarditis, but did not detect such protein in the blood of age-matched control subjects who were vaccinated but did not have the condition. It is not yet known what role, if any, lingering spike protein plays in the development of myocarditis, but clearly, it was not present or an issue for everyone who was vaccinated.
A later study found vaccine-related myocarditis to be linked to immune cell inflammation, undercutting earlier hypotheses that the condition might be due to antibodies attacking heart cells.
Notably, the Circulation study stated that the “results do not alter the risk-benefit ratio favoring vaccination against COVID-19 to prevent severe clinical outcomes.”
“The risks of developing vaccine induced myocarditis are far less than the risks of COVID related complications,” Dr. Lael Yonker, the lead author of the Circulation paper and a pediatric pulmonologist at Massachusetts General Hospital, similarly told us in an email.
“As for advice for vaccination,” she said, “I strongly recommend it for my family, friends and patients.”
Studies have consistently shown that myocarditis is much more likely to result from a COVID-19 infection than a vaccine. A possible exception to this, based on a U.K. study, is for males 40 years old and younger. Still, when factoring in the other risks of infection, vaccination wins out for that demographic, too.
Vaccine-related myocarditis is also less serious and is associated with better outcomes than COVID-19-related myocarditis.
Offit noted that the risk of vaccine-related myocarditis appears to have gone down over time, just as the risk of COVID-19 has decreased. He did not think healthy, young people necessarily need annual shots — but didn’t recommend against it.
“I think it’s low risk, low reward for that group,” he said.
Bhattacharya, too, said that he would have been more sympathetic if the Florida guidance had focused on young males.
“But if you’re saying everyone shouldn’t get it,” he said of the mRNA COVID-19 vaccines, “that’s clearly not based on any science.”
‘Nonsense’ DNA Integration Claim
As we said, the guidance repeated the claim that the mRNA vaccines pose a “unique” risk of DNA integration, citing a problematic report that has not been published.
Offit called the concern “nonsense,” noting the litany of challenges facing foreign DNA in cells that make it exceedingly unlikely that any trace DNA fragments left over after purification would be able to integrate into a person’s genome.
He also called it “illogical,” since anything grown in cells — including the Novavax vaccine and many other vaccines — will also have residual DNA. “It’s just fear mongering,” he added.
The Therapeutic Goods Administration, Australia’s equivalent of the FDA, recently addressed this misinformation, explaining that the reports that claim DNA contamination use improper methods, have issues with samples and “fail to apply the required scientific rigor expected in pharmaceutical testing.” The results, the agency said, are “not robust or reliable.”
The TGA went on to say that it has independently tested 27 batches of COVID-19 mRNA vaccines, and found that all were below the regulatory limit for residual DNA. It also noted that there is no evidence of mRNA vaccines or other medicines in use in Australia ever integrating residual DNA into a person’s genome — even something such as insulin, which is injected several times a day for many years.
For more on these claims, see our stories “Faulty Science Underpins Florida Surgeon General’s Call to Halt mRNA COVID-19 Vaccination” and “COVID-19 Vaccines Have Not Been Shown to Alter DNA, Cause Cancer.”
Misconstrued Effectiveness Concerns
Citing a study from the Cleveland Clinic and one from Qatar, the Florida guidance also misleadingly claimed that studies show that COVID-19 vaccination is counterproductive, increasing the risk of infection or showing “negative effectiveness” after four to six months.
Overwhelming evidence indicates COVID-19 vaccines increase protection against the coronavirus, although that protection wanes. On occasion, due to the observational design of the studies, some effectiveness estimates dip below zero, usually many months after vaccination and for less severe outcomes, such as infection. But this is unlikely to mean that the vaccine is actually increasing a person’s risk.
The Qatar study, for example, estimated the effectiveness of second and third doses of the original Pfizer/BioNTech and Moderna vaccines against BA.1 and BA.2 omicron variants. The headline results showed “moderate, and short-lived” protection against symptomatic infection and “strong and durable protection against COVID-19 hospitalization and death.”
The Florida guidance was focused on a minor finding from the paper that the authors did not even think was real: negative effectiveness of a second dose against infection, after seven or more months.
“Negative estimated effectiveness likely reflects an effect of bias and not true negative biological effectiveness,” the authors wrote. They went on to say that the result could have come about if people were more social or took fewer precautions after being vaccinated, or if the unvaccinated group had already preferentially developed immunity from infection — a form of bias known as depletion-of-susceptibles. Both would underestimate vaccine effectiveness.
Experts have previously told us that bias is also likely behind a similar result in the Cleveland Clinic paper. As we’ve written, that study did not show that vaccines increase the risk of infection, as many on social media have claimed.
Instead, researchers found an association — not a causal relationship — between hospital workers receiving more vaccine doses and testing positive for a coronavirus infection. This could be due to multiple other factors, since the study was not a randomized controlled trial, and there could be important differences that were unaccounted for between the people who received more doses and those who received fewer.
Similar to the Qatar study, the main finding of the Cleveland Clinic paper was actually that a booster dose was associated with a reduced risk of infection during the period when the variant was a good match to the vaccine.
Inaccurate or misleading claims about negative effectiveness have been a common form of COVID-19 vaccine misinformation, with people opposed to vaccination cherry-picking these results and misrepresenting them.
‘Overall Health’ Not a Replacement for Vaccination
The bulletin concluded by encouraging Floridians “to prioritize their overall health” by staying active, eating well and spending time outdoors. It also connected those activities to COVID-19, stating, “Improving habits and overall health help manage and reduce the risk of heart disease, type 2 diabetes, and obesity, risk factors for serious illness from COVID-19.”
Watching your diet and getting exercise, of course, is good advice, generally. But few people can modify their behaviors fast enough to reduce the risk of a bad coronavirus infection this season. It’s also a very indirect approach to reducing risk when a highly specific tool — a vaccine — is available.
“The only way that your immune system will recognize a specific virus is if you’re either naturally infected or vaccinated,” Offit said. “And vaccination is always the better choice.”
One of the great strengths of the human immune system is the ability to “remember” past exposures to pathogens. That way, when a person encounters the pathogen again, they can more quickly and effectively fight off the invader. This is made possible by the adaptive immune system, which involves the production of immune cells and antibodies that specifically target that particular pathogen.
Being healthy or even having a “strong” immune system is not a replacement for COVID-19 vaccination, as these do not provide specific, adaptive immunity to the coronavirus.
Editor’s note: FactCheck.org does not accept advertising. We rely on grants and individual donations from people like you. Please consider a donation. Credit card donations may be made through our “Donate” page. If you prefer to give by check, send to: FactCheck.org, Annenberg Public Policy Center, 202 S. 36th St., Philadelphia, PA 19104.