Florida’s surgeon general on Wednesday called for a halt to the use of Covid vaccines, citing widely debunked concerns that contaminants in the vaccine can permanently integrate into human DNA.
“These vaccines are not appropriate for use in human beings,” Dr. Joseph Ladapo, the state’s surgeon general and highest-ranking health official, said in a statement released by the Florida Department of Health.
Federal health officials and other experts have repeatedly sought to counter Dr. Ladapo’s erroneous comments about the vaccines, noting that careful review of the scientific evidence has found no basis for his declarations.
The Food and Drug Administration said on Wednesday that it had not identified any “safety concerns related to the sequence of, or amount of, residual DNA.”
The Covid vaccines made by Pfizer and Moderna use so-called messenger RNA, or mRNA, a type of genetic material, to direct the body to make immune molecules against the coronavirus.
Dr. Ladapo’s latest statement amplifies Florida’s escalating anti-vaccine stance. He was appointed surgeon general in 2021 by Gov. Ron DeSantis, a Republican, and has since increasingly aligned himself with anti-vaccine claims that the shots cause serious harm.
In March 2022, Dr. Ladapo released guidance advising against healthy children receiving the vaccines, despite studies showing that the vaccines are safe and effective at all ages. That fall, he recommended that young men between the ages of 18 and 39 avoid mRNA vaccines because of a high risk of cardiac death, reaching that conclusion by altering the findings of a state-led study.
Last year, Dr. Ladapo attributed life-threatening conditions reported from Florida and elsewhere to the Covid vaccines, prompting the F.D.A. to publish a rebuttal. And in September, Florida advised all residents under the age of 65 to skip the vaccines.
Dr. Ladapo’s latest contention is “very irresponsible,” said John Wherry, a vaccine expert and director of the Institute for Immunology at the University of Pennsylvania.
“He has, however, demonstrated a tenuous grasp of science and medicine in general over the course of the pandemic so this is not surprising,” Dr. Wherry said.
Neither Mr. DeSantis’s presidential campaign nor his governor’s office immediately responded to requests for comment. The Florida Department of Health did not immediately respond to a request for comment on the rationale for Dr. Ladapo’s assessment or its potential effect on vaccine uptake in the state.
Dr. Ladapo’s intensifying rhetoric has prompted federal agencies to directly address his claims. In a letter to Dr. Ladapo published in December, the F.D.A. detailed the many reasons his claims are implausible.
The vaccines have saved millions of lives, the agency said in a statement on Wednesday. It chastised Dr. Ladapo for fueling misinformation that contributes to low vaccine uptake and continued death and serious illness from Covid.
Covid is once again resurgent across the United States, and fewer than one in five American adults has received the latest shots. Even among those 75 and older, who are at highest risk from Covid, only about one in three have received the most recent version of the vaccine. Florida’s vaccination rates are among the lowest in the country.
“The F.D.A. stands firmly behind the safety, effectiveness and manufacturing quality of the approved and authorized Covid-19 vaccines, and respectfully disagrees with the Florida Surgeon General’s opinion,” the agency said.
In his declaration on Wednesday, Dr. Ladapo contended that contaminants in the vaccines might integrate into human DNA, theoretically causing chromosomes to become unstable and healthy cells to become cancerous.
Experts in virology and immunology said those ideas were nonsensical.
“You will see a mighty lot of ‘mights’ in there,” said John Moore, a virologist at Weill Cornell Medicine in New York. “There’s no evidence that any of this chain of ‘mights’ actually happens or even could happen.”
DNA vaccines have many orders of magnitude more DNA than is present as an mRNA vaccine contaminant, and yet have never been associated with cancer, Dr. Moore noted.
“Every member of my immediate family has had mRNA vaccine doses,” he added. “I am absolutely certain none of them is at risk of contracting cancer as a result.”
For Dr. Ladapo’s claim to be true, humans would need to have an enzyme that can incorporate foreign DNA into their genomes.
“We don’t have one,” said Dr. Eric Rubin, a member of the F.D.A.’s vaccine advisory committee and the editor in chief of the New England Journal of Medicine.
“There is no mechanism and no credible evidence,” Dr. Rubin said.
Mike Ives and Nicholas Nehamas contributed reporting.