A measles, mumps, and rubella vaccine is prepared at Seminole Hospital District in Seminole, Texas, Feb. 24, 2025. The Trump administration is expected to announce in the 2026 that American children should be immunized according to a different schedule with fewer vaccines — on used by the much smaller, largely homogenous country of Denmark. (Desiree Rios/The New York Times)
Over the last year, Health Secretary Robert F. Kennedy Jr. and his appointees have taken tentative steps toward his long-standing goal of remaking the childhood vaccination schedule.
But emboldened by a directive from President Donald Trump, Kennedy is now poised to make a seismic shift. He is expected to announce in the new year that American children should be immunized according to a different schedule with fewer vaccines, used by the much smaller, largely homogenous country of Denmark.
A wholesale revision of the schedule would bypass the evidence-based, committee-led process that has underpinned vaccine recommendations in the country for decades, and could affect whether private insurance and government assistance programs will cover the shots.
And many medical experts worry that losing strong endorsements of some vaccines will create financial and logistical hurdles to obtaining them, further erode Americans’ confidence in immunizations and increase the chances of disease outbreaks. Measles and whooping cough are already resurgent in multiple states because of dropping vaccination rates.
It is states, not the federal government, that decide which shots are mandated for children to attend day care or kindergarten. And the specifics of changes in the vaccine schedule are as yet unclear.
Also unclear is whether any changes will still protect vaccine manufacturers from being sued for claims of harm. Without that guarantee, companies might face “frivolous” lawsuits and flee the American market as they did before such protections were instituted in the 1980s, some vaccine experts warned.
Trump directed Kennedy to align recommendations for childhood vaccines with “best practices from peer, developed countries,” calling the United States “a high outlier in the number of vaccinations recommended for all children.” He pointed to Denmark, Germany and Japan as examples of nations that immunize against fewer diseases.
The directive said that health officials should make the changes “while preserving access to vaccines currently available to Americans,” suggesting to some public health experts that those who wish to get them may still be able to do so in consultation with a health care provider.
Still, even if only some Americans follow a reshaped schedule that includes fewer immunizations, medical experts said, it is almost certain to lead to more cases of infectious disease.
“They’re going to bring back suffering and death,” said Dr. Sean O’Leary, chair of the infectious disease committee for the American Academy of Pediatrics. “I don’t say that with any hyperbole. That’s exactly what’s going to happen.”
The Department of Health and Human Services did not immediately respond to a request for comment.
The United States currently recommends immunizing all children against 17 diseases. Adopting Denmark’s schedule would skip shots against seven of these: respiratory syncytial virus — the leading cause of infant hospitalizations in the United States — influenza, rotavirus, chickenpox, meningitis, hepatitis A and hepatitis B.
Health officials in Denmark and Germany said they were baffled by the Trump administration’s push to emulate their countries. Traditionally, they have looked to the United States as a leader for its meticulous process of review and recommendation of vaccinations.
The officials noted that the childhood vaccination schedule in the United States had been tailored for the country’s large and diverse population and patchy system of medical care. Denmark and Germany have comprehensive free prenatal care and an infant mortality rate that is about half that of the United States.
“It’s not at all fair to say look at Denmark unless you can match the other characteristics of Denmark,” said Anders Hviid, who leads research on vaccine safety and effectiveness at the Statens Serum Institut, Denmark’s equivalent of the U.S. Centers for Disease Control and Prevention.
Denmark’s health care system purchases vaccines for its citizens. It omits shots for some diseases from the childhood schedule because they do not pose enough of a problem there to make the vaccines cost-effective, not because of concerns about safety, Hviid said.
He said he was struck by the irony of Kennedy and his associates holding Denmark up as an ideal because many of the studies that disproved Kennedy’s theories of vaccine harm were led by Danish health officials.
Research by Hviid and his colleagues recently showed that aluminum salts, which are used to enhance the immune response produced by vaccines, are not associated with any of 50 conditions including allergies, asthma and autism.
Kennedy has said that aluminum can harm the brain, and has panned that study as a “deceitful propaganda stunt by the pharmaceutical industry.” The federal vaccine committee plans to explore alternatives for alum, the members said at their meeting this month.
In the United States, “it turns out to get crazier and crazier in public health from month to month,” Hviid said. “It is surreal, and it is difficult, from a Danish perspective, to understand what’s going on.”
Dr. Reinhard Berner, a pediatric infectious diseases expert in Germany and chair of STIKO, the independent committee that recommends vaccines for Germans, said the decisions in his country were not based on safety concerns, but on the prevalence of diseases there.
In the United States, a federal panel called the Advisory Committee on Immunization Practices, or ACIP, recommends vaccines for Americans. By law, insurance companies are required to cover the shots that the panel recommends.
Over decades, the committee has built the childhood vaccination schedule after methodically reviewing data on the safety and effectiveness of each shot, the ideal timing for its administration, whether it should be given with other shots and other practical considerations.
The committee members typically included immunologists, pediatricians and other health care professionals with expertise in vaccines. Those experts were vetted over many months before being invited to join the committee.
Kennedy in June dismissed all 17 voting members of the advisory committee. He later replaced them with 12 new members, few of whom have vaccine expertise and many of whom share Kennedy’s skepticism of vaccines.
O’Leary said the vaccines recommended for American children by previous advisory committees had been included after careful consideration of the risks the diseases posed to Americans. The rotavirus vaccine, for example, which is not included in Denmark’s list, nearly eliminated the tens of thousands of hospitalizations the disease caused in the United States each year.
Likewise, before routine vaccination, chickenpox led to as many as 13,500 hospitalizations and killed up to 150 people in the United States annually. Shingles, which can be caused by the same virus later in life, can be debilitating and excruciatingly painful.
“So which diseases are they choosing to bring back to the U.S.?” O’Leary said. “Do we want to bring back deaths from chickenpox?”
The pediatrics academy’s own recommendations still align with the schedule put together by the previous members of ACIP. At least for the moment, many states, and most professional societies and insurance companies, have signaled that, they, too, will stick with that schedule, rather than follow the changes the Trump administration appointees proposed.
If states did follow a new schedule, they might open themselves up to lawsuits from parents who were unable to get the shots for their children.
Still, the disagreements among officials will undermine trust in vaccines, O’Leary warned.
So far this year, the country has recorded nearly 2,000 cases of measles in 49 outbreaks, the most since the United States was declared free of the disease 25 years ago. Most of the cases have occurred in pockets of low vaccination. If the outbreaks do not abate, the country is in danger of losing its elimination status in late January.