Dr. Peter Marks, the leading vaccine expert at the Department of Health and Human Services resigned to protest Secretary Robert F. Kennedy Jr.’s persistent lies about the efficacy of vaccines. At his Senate hearings, Kennedy assured the committee that his days as a vaccine opponent were over. He lied.

The New York Times reported:

The Food and Drug Administration’s top vaccine official, Dr. Peter Marks, resigned under pressure Friday and said that Health Secretary Robert F. Kennedy Jr.’s aggressive stance on vaccines was irresponsible and posed a danger to the public.

“It has become clear that truth and transparency are not desired by the secretary, but rather he wishes subservient confirmation of his misinformation and lies,” Dr. Marks wrote to Sara Brenner, the agency’s acting commissioner. He reiterated the sentiments in an interview, saying: “This man doesn’t care about the truth. He cares about what is making him followers.”

Dr. Marks resigned after he was summoned to the Department of Health and Human Services Friday afternoon and told that he could either quit or be fired, according to a person familiar with the matter.

Dr. Marks led the agency’s Center for Biologics Evaluation and Research, which authorized and monitored the safety of vaccines and a wide array of other treatments, including cell and gene therapies. He was viewed as a steady hand by many during the Covid pandemic but had come under criticism for being overly generous to companies that sought approvals for therapies with mixed evidence of a benefit.

His continued oversight of the F.D.A.’s vaccine program clearly put him at odds with the new health secretary. Since Mr. Kennedy was sworn in on Feb. 13, he has issued a series of directives on vaccine policy that have signaled his willingness to unravel decades of vaccine safety policies. He has rattled people who fear he will use his powerful government authority to further his decades-long campaign of claiming that vaccines are singularly harmful, despite vast evidence of their role in saving millions of lives worldwide.

“Undermining confidence in well-established vaccines that have met the high standards for quality, safety and effectiveness that have been in place for decades at F.D.A. is irresponsible, detrimental to public health, and a clear danger to our nation’s health, safety and security,” Dr. Marks wrote.

Mr. Kennedy has, for example, promoted the value of vitamin A as a treatment during the major measles outbreak in Texas while downplaying the value of vaccines. He has installed an analyst with deep ties to the anti-vaccine movement to work on a study examining the long-debunked theory that vaccines are linked to autism.

And on Thursday, Mr. Kennedy said on NewsNation that he planned to create a vaccine injury agency within the Centers for Disease Control and Prevention. He said the effort was a priority for him and would help bring “gold-standard science” to the federal government.

An H.H.S. spokesman said in a statement Friday night that Dr. Marks had no place at the F.D.A. if he was not committed to transparency.

In his letter, Dr. Marks mentioned the deadly toll of measles in light of Mr. Kennedy’s tepid advice on the need for immunization during the outbreak among many unvaccinated people in Texas and other states.

Dr. Marks wrote that measles, “which killed more than 100,000 unvaccinated children last year in Africa and Asia,” because of complications, “had been eliminated from our shores” through the widespread availability of vaccines.

Dr. Marks added that he had been willing to address Mr. Kennedy’s concerns about vaccine safety and transparency with public meetings and by working with the National Academies of Sciences, Engineering and Medicine, but was rebuffed.

With the outbreak of measles in several states, Kennedy’s refusal to advocate immunization is a danger to public health. Only someone as dumb or malevolent as Trump could put a conspiracy theorist and vaccine opponent in charge of public health.