A week after Donald Trump made a series of misleading claims about vaccines – including that some injections look “like the size of a soda bottle” – the Centers for Disease Control and Prevention (CDC) released the latest data on national kindergarten vaccination rates.

CDC communications downplayed the changes – a three-sentence announcement said, “overall vaccination rates among kindergarteners remained high” – but medical experts immediately saw cause for concern in the trends.

“There’s been a decrease in immunization rates in all vaccines. There’s a decrease in immunizations in more than half the states, as opposed to the year before. There are at least 280,000 kindergarteners who did not get the [measles, mumps and rubella vaccine],” said Dr Paul Offit, director of the Vaccine Education Center and an attending physician in the division of infectious diseases at Children’s Hospital of Philadelphia (Chop).

Additionally, non-medical exemptions for vaccines for kindergarteners grew by 17% over the last school year – the highest single-year increase ever, from 3.6% to 4.2% nationwide.

Pediatricians, local health officials and vaccine experts, such as Offit, described the latest vaccine data as evidence of how the administration – through almost too many means to enumerate – has sowed confusion about the safety and benefits of vaccines, leading to depressed vaccination rates and parents’ efforts to opt-out.

“If we had a secretary of Health and Human Services (HHS) who was an actual secretary of HHS instead of an anti-vaccine activist and science denialist, he would stand up in front of the American public and say, ‘Vaccinate your children.’ – please, vaccinate your children,” he said.

Even so, the picture is not entirely bleak. The overwhelming majority of American parents still vaccinate their children. Data released by the CDC showed that vaccination dropped by only 0.1% between the last two school years, to 92.4% of children vaccinated with the measles, mumps and rubella (MMR) vaccine.

While there is a high overall rate of vaccination, parents who refuse vaccination are not evenly distributed around the United States. Often, low vaccination rates are found in pockets, such as in Idaho or Ohio. The US is currently experiencing the worst year for measles since 1991, where there have been hundreds of cases in Utah and South Carolina.

“In Cleveland, for example, a couple years ago, our percentage of kindergartners being up-to-date on vaccines was 68%,” said Dr David Margolius, director of the Cleveland Department of Public Health. “This past school year, we’re up to 76%. We are doing the work.”

However, “the federal government is causing more and more confusion, and that’s washing out the effects and the work that all of us are trying to do,” Margolius added.

Vaccines have saved millions of lives globally. Widespread measles vaccination alone is credited with saving 59 million lives between 2000 and 2024, according to the World Health Organization. Prior to widespread US vaccination in the mid-20th century, measles killed roughly 500 people per year.

Still, vaccines have been under attack for decades by well-known activists who have linked vaccines to rising rates of autism. Autism has been linked to some infections, parental age and genetics, but because it is a complex spectrum disorder, experts argue there will be more than one single cause, according to Chop.

The height of recent confusion came directly from the White House. On 10 August, the US president sat and signed an executive order calling for fewer vaccines, flanked by Robert F Kennedy Jr and his new nominee for the Food and Drug Administration (FDA), Dr Heidi Overton. He then proceeded to link vaccines to autism (without evidence) and soda bottle-sized doses (a wild falsehood), assertions he said were supported by “gold standard” science (they’re not).

He then signed an executive order that called for the US to reduce the number of vaccines children routinely receive, from 17 diseases to 11, and critically administer the MMR vaccines as three separate doses.

“We have the MMR, which hopefully will be split up. We have the MMR, we want it in three separate vaccinations given at separate times,” said Trump. “Together, there could be a possibility they’re quite lethal, and separately it looks like they are not at all lethal,” he said, without any evidence.

Trump clearly stated the potential impact of this: “You should have five separate visits for vaccines, rather than getting them all in the same day.”

Aside from the obvious logistical barriers for parents of newborns, who would suddenly be tasked with medically unnecessary doctor’s visits, there are legal and manufacturing barriers. Drug companies have not produced separate measles, mumps and rubella vaccines in decades, and doing so would require companies to reengineer supply lines on some of their least profitable products.

Then legally, the federal government may recommend vaccines, but it’s the states who set policies about the vaccines children must receive before attending public school – requirements that are arguably the most effective way to get children vaccinated.

Indeed, one of the quirks of American public health law is that the constitution delegates the health and welfare of Americans to states. Trump’s symbolic order marks a high point, but certainly not the depth of anti-vaccine advocacy.

The MMR vaccine has been targeted since 1998, when discredited former doctor Andrew Wakefield published studies in The Lancet linking the two. His studies fell apart under scrutiny and are now retracted. Investigative journalist Brian Deer revealed that Wakefield patented a measles vaccine months before his study was released, and Wakefield infamously called for separating the measles, mumps and rubella vaccines.

Kennedy took up the mantle before he became health secretary. He led an anti-vaccine advocacy group called Children’s Health Defense, a non-profit that was one of the world’s most prolific spreaders of false and misleading vaccine claims. His 2023 salary at the nonprofit was $325,056 (while on leave campaigning for president) and $510,515 in 2022, according to nonprofit tax filings. Additionally, Kennedy earned $1.5m for “referral fees” from Wisner Baum and $62,500 from Morgan & Morgan, both law firms leading vaccine injury cases, according to ethics disclosures first published by Politico.

“The first concern with MMR is typically autism,” said Dr Mysheika Roberts, commissioner of the public health department in Columbus, Ohio. Dr Roberts was scheduled to serve on the CDC’s advisory committee on immunization practices (ACIP) before being fired by Kennedy in June 2025.

Kennedy has continued his work against vaccines as health secretary, often under the banner of “gold standard” science. He falsely claimed that the MMR vaccine contained “aborted fetal debris”, and in the midst of a measles outbreak in Texas in 2025, recommended vitamin A supplementation, which led to children being hospitalized for liver dysfunction.

Kennedy amended the CDC’s website to assert that, “The claim ‘vaccines do not cause autism’ is not an evidence-based claim because studies have not ruled out the possibility that infant vaccines cause autism.” In fact, studies have examined the claim that vaccines cause autism and, across large population studies in multiple countries, found no evidence for the claim.

He disbanded the CDC’s group of expert advisors on vaccines, and replaced them with a group ideologically aligned with himself. The recommendations of Kennedy’s hand-picked group are now the subject of litigation.

What’s more, changing federal recommendations have made it significantly harder to get certain vaccines, such as for Covid-19. That led a pregnant doctor to sue the HHS because she could not obtain the Covid-19 shot.

“[Kennedy] is waging a war against vaccines because he believes … there is an epidemic of chronic diseases in this country. He believes vaccines are a major cause of that epidemic, and therefore he is going to do everything he can to lessen vaccines.

“He said that when he runs into a parent holding a child on a hiking or walking path, he goes up to them and says, ‘Don’t vaccinate your child,’” said Offit. “That’s who he is – a zealot – and that’s why he ignores the vaccine epidemic data.”