Donald Trump, former Covid-19 vaccine booster, is now the nation’s most high-profile critic of immunization mandates.

The former president has on the campaign trail promised to strip funding from schools with vaccine requirements and lambasted independent candidate Robert F. Kennedy Jr. as a “fake” anti-vaxxer, while obscuring his role in speeding the development of the Covid shot when he was president during the pandemic.

Trump’s new anti-vaccine persona could have far-reaching consequences if he’s elected to a second stint as president with far-reaching administrative powers. Public health experts say a White House opposed to immunization mandates could potentially cause upticks in cases of measles, polio and other vaccine-preventable diseases, or hamper efforts to fight a future pandemic.

The CDC could pare back the number of vaccines it recommends children receive or eliminate those recommendations entirely. The CDC could change the paperwork required to be shared with parents to make vaccines sound less safe than they are. Or the FDA could increase the number of years of safety testing required for new vaccines and impose other onerous requirements for vaccines to be approved in the U.S.

Trump also could, as a thank-you to vaccine skeptics for their support in November, appoint someone who opposes the government’s traditional role in promoting vaccines, such as Kennedy or Florida Surgeon General Joseph Ladapo, who called for a pause in the use of Covid-19 mRNA vaccines and did not encourage parents to vaccinate their children during a recent measles outbreak.

“The short version is they can create — through their control over money, control over processes and infrastructure at the federal level — enormous havoc,” said Georges Benjamin, executive director at the American Public Health Association. “If you want to see an organization not function, put somebody that’s not qualified to be there, or who may have credentials on paper but is not motivated to really do the job in a way that enhances the public’s health.”

Kennedy’s campaign did not respond to a question about whether he would consider joining a future Trump administration; the Florida Department of Health did not respond to requests for comment from Ladapo.

The former president’s growing criticism of immunization mandates comes as Kennedy tries to woo Trump’s increasingly vaccine-skeptical MAGA base, and as suspicion about the Covid-19 shots spills into other routine childhood immunizations. A POLITICO | Morning Consult poll last fall showed that Republican voters are less likely than Democrats or independents to say vaccines are safe for children; Trump primary supporters were twice as likely as other Republicans to say such vaccines are unsafe, the poll found.

The Trump campaign has previously said that the former president is threatening to take away funding only from schools that mandate the Covid-19 vaccine, not other vaccines. Public health experts don’t think Trump is personally opposed to immunization, and Trump and his wife, Melania, received the Covid-19 shot and in 2021 encouraged “everyone” to “go get your shot.” And states are responsible for establishing most immunization policies.

But public health experts remain concerned about what Trump might do as president or whom he might appoint.

Trump’s campaign did not answer specific questions about what other vaccine policies the former president would or would not adopt, or whether he would consider appointing vaccine-skeptical individuals. The campaign pointed back to his promise to defund schools with vaccine mandates, which spokesperson Caroline Sunshine said in an email still stands.

Former Trump administration officials argue some policy changes are needed to address concerns about how the government communicated with the public during the pandemic and that those policies aren’t anti-vaccine. The conservative Heritage Foundation’s “Project 2025” blueprint, for instance, recommends breaking up the CDC to separate its scientific and policymaking functions.

“Because CDC’s credibility has been so damaged because it bungled the Covid response, people rightfully have a lot more questions about recommendations for everything, vaccine-related and otherwise,” said Roger Severino, vice president of domestic policy at the Heritage Foundation and director of HHS’ Office for Civil Rights under Trump. He added that he doesn’t question the safety and efficacy of any vaccine, but that “there is an additional burden on the CDC to explain with hard science the rationale for all the vaccines on the schedule being taken in combination.”

The CDC declined to comment. Former CDC Director Robert Redfield, who served under Trump, did not respond to a request for comment.

Paul Mango, former deputy chief of staff for policy at HHS under Trump, said it’s unlikely the former president would prioritize anti-vaccine policies or appoint anti-vaccine officials in a second administration. Trump did, after all, champion Operation Warp Speed, a public-private partnership that helped develop the Covid-19 vaccine in record time.

“I guess it’s always a possibility, but I think it’s an extremely low probability,” Mango said. “I just don’t see that as a priority. If there’s someone who’s great at all of that other stuff and they happen to be anti-vaccine, I don’t know, I don’t know who that individual is, but I don’t think that would be a selection criterion. I really can’t imagine that despite the political rhetoric and the campaign rhetoric.”

But Trump rewarded evangelicals for their support in 2016 with three conservative Supreme Court justices who overturned Roe v. Wade, and public health experts fear what a similar reward might look like for vaccine skeptics. They worry he might appoint someone like Kennedy, who Trump, after he was elected in 2016, asked to chair a “vaccine safety task force,” or Ladapo to a top health position.

Such appointments would represent a stark departure from the broadly respected personnel who served in the Trump administration, such as Alex Azar, a George W. Bush HHS appointee who was a top executive at the drugmaker Eli Lilly; Scott Gottlieb, who worked at the FDA under Bush; and Jerome Adams, who ran Indiana’s health department under then-Gov. Mike Pence. It would also deviate from the approach he took during the Covid-19 pandemic, putting scientists and doctors, such as Deborah Birx, at the forefront of the White House’s messaging.

“If he appoints any of those Fox News talking heads in a leadership position of the CDC or NIH or FDA, absolutely they could do a lot of damage,” said Peter Hotez, co-director of the Texas Children’s Hospital Center for Vaccine Development.

Kennedy’s campaign, in a statement, said that he “opposes all vaccine mandates” but has “no intention of amending the CDC childhood recommended vaccine schedule” and would “not use the federal government to force state governments or schools to change their policy on vaccines” if elected president.

A second Trump administration could effect significant change even just by making tweaks to two top vaccine advisory committees — the CDC’s Advisory Committee on Immunization Practices and the FDA’s Vaccines and Related Biological Products Advisory Committee. It could either appoint vaccine-skeptical individuals to the bodies or scrap them entirely.

Such a move would likely have immediate impacts on states, many of which point directly to CDC and ACIP recommendations in their immunization statutes. The CDC puts out yearly recommended immunization schedules for both children and adults.

“Imagine what happens if CDC guidance changes to, ‘Vaccination is a question for families. CDC recommends that families talk to their provider or minister about vaccines,’ and doesn’t recommend anything,” said Wendy Parmet, who directs the Northeastern University Law School’s Center for Health Policy and Law. “Some state laws are going to change with a blink of an eye.”

The FDA, in a statement, said advisory committee members must be “technically qualified experts in their field” and be “able to analyze detailed scientific data and understand its public health significance.” It added that while committees provide recommendations, final decisions are made by the FDA.

A future administration could also use the power of the purse, like withholding funding for the federal Vaccines for Children Program, to persuade states to adopt or remove certain vaccine policies. It could defund or reduce funding for the CDC’s work on vaccine recommendations and promoting vaccination. CMS could remove vaccination as a quality measure. The NIH could decide not to fund certain kinds of vaccine research.

Public health experts additionally fear Trump could also end all federal vaccine mandates, including for members of the military, which they say could undermine the nation’s defenses. Military members are required to receive a suite of shots before basic training — against diseases like tetanus, measles and polio — while others have to get additional vaccines protecting them against anthrax or smallpox, though they can opt out on health, administrative or religious grounds.

Even if Trump takes none of those actions — or loses the 2024 election — public health experts warn that the former president’s campaign trail rhetoric is enough to give state and local officials the confidence they need to change their vaccine policies.

Some state and local jurisdictions have already been moving in that direction. In West Virginia, the GOP-controlled Legislature voted to remove vaccine requirements for students in private and parochial schools, though Republican Gov. Jim Justice, who is running for Senate, vetoed the bill. A Houston-area school board voted in May to remove sections from science textbooks that address vaccines.

“Even if it’s your state legislators who are making the decisions that count, if they see a president elected who holds strong anti-vaccine views, or who appoints anti-vaccine administrators, that tells elected officials at the state and local level, ‘Hey, this president was elected on this platform, this must be something that my constituents also care about,’” said Allison Winnike, director of the Western region for the Network for Public Health Law. “It could overnight cause really lasting harms that would take a long time to try to combat.”