The Trump administration overhauled the decades-old childhood vaccination schedule announced by federal health officials on Jan. 5, 2026, sparking alarm among public health experts and pediatricians.
The US childhood immunization schedule, the grid of colored bars that pediatricians share with parents, recommends a set of vaccines from birth through adolescence to prevent several serious infections. Its basic structure has existed since 1995, when health authorities and medical organizations issued a unified national standard, although new vaccines have been added as science has advanced.
That calendar is now being dismantled.
In total, the change reduces universally recommended childhood vaccines from 17 to 11. It moves rotavirus, influenza, hepatitis A, hepatitis B and meningococcus vaccines from routine recommendations to the “shared clinical decision” category, shifting the responsibility for initiating vaccination from the health system to individual families.
Health and Human Services Secretary Robert F. Kennedy Jr., who has questioned the safety of vaccines for decades, justified these changes by citing a 33-page evaluation comparing the U.S. schedule to Denmark’s.
But both countries differ in important ways. Denmark has 6 million people, universal healthcare and a national registry that tracks every patient. On the other hand, the US has 330 million people, 27 million without insurance and a system where millions change providers.
These changes follow the CDC’s decision in December 2025 to remove the recommendation to vaccinate all newborns against hepatitis B, despite no new evidence questioning the long-standing safety of this vaccine.
I am an infectious disease physician who treats vaccine-preventable diseases and reviews the clinical trial evidence behind immunization recommendations. The vaccine schedule was not designed in one fell swoop, but built gradually over decades, shaped by disease outbreaks, technological advances, and lessons learned on how to reduce childhood illness and death.
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The first years
During the first half of the 20th century, most states required students to be vaccinated against smallpox to enter the public school system, but there was no unified national schedule. The combined diphtheria-tetanus-pertussis (DTP) vaccine emerged in 1948, and the Salk polio vaccine arrived in 1955, although recommendations for how and when to administer them varied by state, doctor, and even neighborhood.
The federal government intervened after a tragedy: In 1955, a manufacturing failure at Cutter Laboratories in Berkeley, California, produced batches of the live polio vaccine, causing paralysis in dozens of children. This incident made it clear that vaccination could not be a piecemeal affair and required federal oversight.
In 1964, the US Surgeon General established the Advisory Committee on Immunization Practices (ACIP) to provide expert guidance and recommendations to the CDC on the use of vaccines. For the first time, a single body would evaluate the evidence and issue national recommendations.
New viral vaccines
During the 1960s, vaccines for measles (1963), mumps (1967), and rubella (1969) were licensed, eventually combined into the MMR vaccine in 1971. Each addition followed a similar pattern: a disease that killed or disabled thousands of children, a safe and effective vaccine in trials, and a recommendation that transformed a seemingly inevitable childhood illness into something preventable.
The rubella vaccine protected not only vaccinated children. Rubella, mild in children, is devastating to fetuses, causing deafness, heart defects and intellectual disabilities if pregnant women become infected. The rubella epidemic of 1964-1965 caused 12.5 million infections and 20,000 cases of congenital rubella syndrome, leaving thousands of children deaf or blind. Vaccinating children also helped protect pregnant women by reducing the spread of infection. By 2015, rubella had been eliminated from the Americas.
Hepatitis B and the safety net
In 1991, the CDC added the hepatitis B vaccine at birth. Before that, about 18,000 children contracted the virus each year before their 10th birthday.
Many parents wonder why newborns need this vaccine. The answer lies in biology and the limitations of screening. An infected adult has a 95% chance of clearing the virus, while a baby infected in the first months has a 90% chance of developing chronic infection, and 1 in 4 will eventually die from liver failure or cancer.
Babies can acquire the virus from their mothers during childbirth, from infected household members, or through casual contact in daycares. The virus survives for days on surfaces and is highly contagious.
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Early strategies targeting only high-risk groups failed because many maternal cases were missed. Even today, between 12 and 18% of pregnant women in the US never get tested for hepatitis B. Until ACIP lifted the recommendation in December 2025, the first dose at birth functioned as a safety net, protecting all babies regardless of their mothers’ infection status.
This safety net worked: Hepatitis B infections in American children fell by 99%.
A unified standard
For decades, different medical organizations issued their own, sometimes contradictory, recommendations. In 1995, ACIP, the American Academy of Pediatrics, and the American Academy of Family Physicians jointly launched the first unified national calendar, the predecessor of today’s family grid. For the first time, parents and doctors had a single national standard.
The schedule continued to evolve: ACIP recommended chickenpox vaccines in 1996; rotavirus in 2006, replacing an earlier version recalled for rare side effects; and HPV, also in 2006. Each addition followed a rigorous process: evidence review, risk-benefit analysis, and public advisory committee voting.
More vaccines, less burden
Vaccine skeptics, including Kennedy, wrongly claim that children’s immune systems are overtaxed by increased vaccinations. This argument is used to justify a reduced schedule.
A fact that surprises parents: although recommended vaccines have increased, the number of immune system-stimulating molecules (antigens) has decreased dramatically since the 1980s, which means they are less demanding on the child’s immune system. The whole-cell pertussis vaccine of the 1980s contained about 3,000 molecules; Today the entire calendar has less than 160 antigens, thanks to technological advances that allow targeting only the components necessary for protection.
What’s coming
For decades, ACIP only recommended changes to the children’s schedule when evidence or a clear change in disease risk required it. The January 5 announcement represents a fundamental break: Several vaccines were withdrawn from routine recommendations simultaneously, justified not by new safety data but by comparison with a country with a fundamentally different health system.
Kennedy accomplished this by placing politicians in key vaccine safety positions. Its hand-selected ACIP is made up of members with a history of anti-vaccine stances. The authors of the evaluation that justified the change, senior officials at the FDA and HHS, are long-standing critics of the current schedule. The acting director of the CDC who signed the memo is an investor with no clinical or scientific training.
The practical effect will be felt in clinics across the country. Routine recommendations generate automatic alerts in medical records and allow nurses to vaccinate under standing orders. “Shared clinical decision-making” requires a physician’s intervention in every vaccination decision, creating bottlenecks that will inevitably reduce coverage, especially for the more than 100 million Americans without regular access to primary care.
Major medical organizations, including the American Academy of Pediatrics and the American College of Obstetricians and Gynecologists, have said they will continue to recommend the full set of childhood vaccines. Several states, such as California, New York and Illinois, will follow established guidelines rather than new federal recommendations, creating an unequal scenario where children’s protection will depend on where they live.
This article was originally published by The Conversation
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