Vaccination coverage among U.S. kindergartners slipped once more last school year, while the number of children receiving exemptions from school vaccine rules climbed to a record level, according to federal data released Monday.
The share of children granted vaccine exemptions increased to 4.2%, compared with 3.6% a year earlier. That amounts to an estimated 155,000 kindergartners nationwide during the 2025-26 school year.
It marks the fourth year in a row that the national exemption rate has set a new high. Most of those exemptions were not for medical reasons, but reflected parents choosing to keep children from getting required shots. Exemption rates rose in 41 states as well as Washington, D.C.
Public health specialists say the trend is being fueled in part by turmoil caused by federal health officials and shifting messages around vaccines.
U.S. Health Secretary Robert F. Kennedy Jr., long known as a prominent figure in the antivaccine movement before President Trump appointed him to oversee federal health agencies, has been central to that debate. Over the past 18 months, Kennedy and other federal officials have repeatedly moved to alter and scale back childhood vaccination guidance. Earlier this month, Mr. Trump urged revamped childhood vaccine recommendations built around spacing shots across separate medical visits — an approach major medical groups say is not backed by scientific research.
“The root cause of this is primarily because there’s so much chaos and confusion in vaccination recommendation systems in the last year or so,” said Dr. James Campbell of the American Academy of Pediatrics.
The CDC said 92.4% of kindergartners in the 2025-26 school year received the required measles, mumps and rubella vaccine, a small decline from the prior year. Before the COVID-19 pandemic, MMR coverage stood at 95% — the threshold public health officials say helps prevent a single measles case from turning into a cluster or wider outbreak.
Coverage also declined for several other routine childhood vaccines, including polio, the combined diphtheria-tetanus-pertussis shot, and the first dose of the chickenpox vaccine.
The rate held steady for protection against hepatitis B. But that’s a vaccine given shortly after birth, and it will take a few years before recent federal efforts to upend infant hepatitis B vaccine recommendations would appear in the vaccination rates of kindergartners, Campbell said.
The vaccination numbers were posted as the U.S. experiences its worst year for measles since 1991.
The numbers indicate that more than a quarter of a million children entering kindergarten are susceptible to measles, said Campbell, a University of Maryland researcher who is chair of the AAP’s infectious diseases committee.
Those at-risk kids are not evenly distributed — concentrations of unvaccinated children are higher in some places than others, which helps explain why measles waves vary in intensity.
The CDC data is coming out as school and health officials across the country are encouraging parents to get their children vaccinated as the school year starts.
RELATED: This $1 Pantry Staple Is an Overlooked Longevity Superfood
“Back-to-school season is an important reminder that protecting our children’s health is both a shared responsibility and a shared goal,” North Carolina Health and Human Services Secretary Dev Sangvai said in a statement. “Vaccines help keep our children and teens healthy and in the classroom.”
In the past, the CDC has released the vaccination coverage data in its flagship publication, the Morbidity and Mortality Weekly Report. CDC officials usually speak to the trends and stress the importance of vaccinations.
But since the Trump administration took office early last year, the agency has posted the data online. This year, the agency issued a three-sentence statement that noted a small decline in vaccination coverage among children entering kindergarten and said: “CDC continues to encourage parents to discuss vaccination options with their doctors.”
Public health officials focus on vaccination rates for kindergartners because schools can be cauldrons for germs and launching pads for community outbreaks.
For years, those rates were high, thanks largely to school attendance mandates that required key vaccinations. All U.S. states and territories require that children attending childcare centers and schools be vaccinated against a number of diseases, including measles, mumps, polio, tetanus, whooping cough and chickenpox.
All states allow exemptions for children with medical conditions that prevent them from receiving certain vaccines. And most also permit exemptions for religious or other nonmedical reasons.
In the last decade, the percentage of kindergartners with medical exemptions has held steady, at about 0.2%. But the percentage with nonmedical exemptions has risen.
According to the CDC data, 17.5% of kindergartners had an exemption to one or more vaccines in Idaho in the last school year. But fewer than 0.5% did in Connecticut.
