It used to be fairly easy to dismiss Florida’s surgeon general, Dr. Joseph A. Ladapo, as a clownish anti-vaccine quack posing a danger mostly to residents of his home state.

That has become harder to do as time goes on, as Ladapo has moved from promoting useless treatments for COVID-19, such as the drugs hydroxychloroquine and ivermectin, to waging an ever-expanding fact-free campaign against the leading COVID vaccines.

This month, Ladapo established a new low for himself. In a public advisory issued Wednesday by the Florida Department of Health, he declared the vaccines “not appropriate for use in human beings” and counseled doctors to steer patients to other treatments. He explicitly called for a “halt in the use of COVID-19 mRNA vaccines.”

For several reasons, this advisory ranks as the single most dangerous statement by a government health agency since the start of the pandemic, if not for all time.

First and foremost, it’s based on a claim in a paper co-authored by known anti-vaccine activists that was almost instantaneously debunked upon its publication in October.

Then there’s the public health context: As COVID infections have been surging coast to coast, advisories from public health authorities to resume masking and take other protective measures, such as making sure you’re up to date on vaccinations, are almost invisible.

Even more worrisome, the incidence of other vaccine-preventable diseases may be rising. As many as nine cases of measles have been reported in Philadelphia, some associated with an infection started at a daycare center with a family that violated quarantine rules.

Among the victims, according to the Philadelphia Inquirer, are “an infant who was too young to get vaccinated, an unvaccinated older child and the older child’s unvaccinated parent.”

Nine cases may not sound like a lot — 41 were reported nationwide in 2023 — but they could be a harbinger of worse to come, in clusters in which anti-vaccine propaganda has taken hold.

Finally, one must consider the source. Despite his state post and a tenured position as a professor of medicine at the University of Florida — courtesy of his patron Ron DeSantis, the extremist anti-vaccine Republican governor — Ladapo has zero credibility within the medical establishment. Taking medical advice from Ladapo makes about as much sense as taking investment advice from Sam Bankman-Fried or your view of academic integrity from Christopher Rufo.

Ladapo has become a card-carrying member of the anti-vaccine mafia. Just before Christmas, he appeared on a podcast hosted by anti-vax agitator Del Bigtree, who stirs up his audiences with hysterical rants against vaccines and who was recently appointed communications director for the presidential campaign of notorious anti-vax figure Robert F. Kennedy Jr.

Last January, a faculty committee at the University of Florida medical school found that Ladapo engaged in “careless, irregular and contentious” research practices that may have violated university rules. The committee referred its findings to the university’s research integrity officer, but that officer ruled that since the behavior at issue was performed in Ladapo’s role as surgeon general, not as a UF professor, he had no grounds to take action.

The accusations pertained to Ladapo’s recommendation that males aged 18 to 39 avoid the mRNA vaccines. He claimed that research indicated that for men in that age group, the vaccines presented a heightened risk of cardiac-related death.

In fact, the research indicated no such thing; rather, it showed that the risk of cardiac death from the vaccines was statistically nonexistent and, in any case, was lower than the risk of cardiac death resulting from catching COVID-19. In fact, Ladapo had personally edited the state-sponsored analysis he cited in his recommendation to remove language in earlier drafts stating that there was “little suggestion of any [cardiac] effect immediately following vaccination.”

The Food and Drug Administration has been pushing back against Ladapo’s fire hose of misinformation and disinformation for the better part of a year. Last March, the agency informed him by letter that “overstating the risks, or emphasizing the risks without acknowledging the overwhelming benefits” of the vaccines — as Ladapo had done in his cardiac death warning — “puts people at risk of death or serious illness that could have been prevented by timely vaccination.”

That brings us to Ladapo’s latest adventure in medical quackery, his claim that no one should take the mRNA vaccines. Let’s take a look.

Ladapo’s advice is based on what he says is research that the Pfizer and Moderna mRNA COVID vaccines contain fragments of DNA that are injected into human cells, which they can contaminate and turn into cancer cells.

In a Dec. 6 letter to the FDA and in the Florida Department of Health advisory, Ladapo raised “concerns regarding nucleic acid contaminants in the approved … vaccines, particularly in the presence of lipid nanoparticle complexes, and Simian Virus 40 (SV40) promoter/enhancer DNA. … The presence of SV40 promoter/enhancer DNA may also pose a unique and heightened risk of DNA integration into human cells.”

Followers of anti-vaccine propaganda will find familiar features in this statement. For one thing, it sounds science-y as hell, filled to bursting with abstruse terms and jargon. One would have to be an expert in the field to identify it as total balderdash. The statement also bristles with scary references to DNA contamination and cancer and to “billions of fragments [of DNA] per dose.”

The same goes for Ladapo’s hand-wringing in his statements about the FDA’s 2007 standards for DNA in vaccines and his implication that the COVID vaccines violate those standards.

Fortunately, scientific and medical professionals have weighed in. One is Paul Offit, a vaccine expert at Children’s Hospital of Philadelphia. Offit explains that it’s true that “small amounts of fragmented DNA” are injected into the body with the vaccines.

It’s also irrelevant. For those fragments to affect your DNA, he explains, “things would have to occur, all of which are for the most part impossible.”

The human cell has a panoply of mechanisms to destroy foreign DNA. Even if the fragments managed to penetrate the cell nucleus, which can’t happen, they would have to cut up the existing DNA, which would require a mechanism the fragments don’t have.

“So the chance that DNA could affect your DNA is zero,” Offit said in a video interview with Medpage Today.

As for the Florida statement’s scary references to DNA contamination and cancer and to “billions of fragments [of DNA] per dose,” the vaccines don’t contaminate patients’ DNA, the fragments have no cancer-causing abilities, and that “billions” is, in the context of the vaccines, an incredibly tiny number.

The research paper on which Ladapo based his intimation that the vaccines breach the FDA’s DNA contamination standard is self-refuting. The paper, which was based on an analysis of 24 vials of the mRNA vaccines, actually found that in all cases the fragments were well below the concentration limits set by the FDA.

The FDA, in responding to Ladapo’s Dec. 6 letter, told him that studies of the vaccines showed “no evidence” that the shots damaged recipients’ DNA and that the experience of “hundreds of millions of individuals” who received the vaccines “indicate no evidence indicative of genotoxicity.”

On the other hand, “the challenge we continue to face is the ongoing proliferation of misinformation and disinformation about these vaccines which results in vaccine hesitancy that lowers vaccine uptake,” the FDA lectured Ladapo. “Given the dramatic reduction in the risk of death, hospitalization and serious illness afforded by the vaccines, lower vaccine uptake is contributing to the continued death and serious illness toll of COVID-19.”

In the words of the veteran pseudoscience debunker David Gorski, disinformation like Ladapo’s output is “not about science. It’s about fear-mongering about vaccines.”

Ladapo’s words and actions have surely contributed to his state’s pathetic performance in getting its citizens vaccinated against COVID. With 11.6% of its population fully vaccinated with a booster as of last May, Florida had a rate among the lowest in the nation. (California’s rate was 20.6%.) Among those 65 and older — purportedly the population that Florida strives to protect — only 31.2% were fully vaccinated. (California: 48.3%.)

Florida’s death rate from COVID of 375 per 100,000 people is among the worst in the country. (California: 283.) You can ignore the defense that the difference is due to Florida’s relatively older population; states with even older median ages have done much better: Vermont (170), New Hampshire (245) and Maine (252). The difference is the indifference of Ladapo and DeSantis to their own residents’ health.

Ladapo’s colleagues in science and medicine face the challenge of understanding what drives someone with Ladapo’s credentials — a Harvard education and a stint on the medical faculty at UCLA — to descend so deeply into professional irresponsibility.

“It is hard to believe that Dr. Ladapo actually issued that statement,” Offit said of Ladapo’s advice to avoid the vaccines. “Scaring people unnecessarily like this has been hard to watch.”