Kindergarten vaccination rates in the United States continued to decline during the 2025-2026 school year, while the proportion of children with vaccination exemptions reached an all-time high, according to federal data released Monday.
The fraction of children exempted from vaccine requirements rose to 4.2%, an increase from 3.6% the previous year, affecting an estimated 155,000 children nationwide. This marks the fourth consecutive year that the national average exemption rate has set a new record, with the majority of these exemptions being for nonmedical reasons. Exemptions saw an increase in 41 states and the District of Columbia.
Experts attribute this trend to perceived inconsistencies in federal health guidance. U.S. Health Secretary Robert F. Kennedy Jr., who has been a prominent figure in the vaccine-hesitant movement, has been leading federal health agencies. In the past 18 months, Kennedy and other federal officials have proposed changes and reductions to childhood vaccination recommendations. Earlier this month, President Trump also called for revised childhood vaccination guidelines, suggesting that shots be administered over separate visits.
"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. Campbell, a researcher at the University of Maryland and chair of the AAP's infectious diseases committee, noted that the data indicates over a quarter of a million children entering kindergarten are susceptible to measles.
The Centers for Disease Control and Prevention (CDC) reported that 92.4% of kindergartners received their required measles-mumps-rubella (MMR) shots, a slight decrease from the prior year. Prior to the COVID-19 pandemic, the MMR vaccination rate stood at 95%, a level generally considered sufficient to prevent widespread outbreaks.
Vaccination rates also fell for polio, the combination vaccine for diphtheria, tetanus, and pertussis (DTaP), and the first dose of the chickenpox vaccine. The rate for the hepatitis B vaccine remained steady, though federal efforts to alter infant hepatitis B vaccine recommendations are not yet reflected in kindergarten vaccination data, as the vaccine is typically administered shortly after birth.
These declining vaccination numbers coincide with the U.S. experiencing its most significant measles outbreak since 1991. The uneven distribution of unvaccinated children across different regions contributes to the varying intensity of measles outbreaks.
As the school year begins, school and health officials are urging parents to ensure their children are vaccinated. "Back-to-school season is an important reminder that protecting our children’s health is both a shared responsibility and a shared goal," said North Carolina Health and Human Services Secretary Dev Sangvai in a statement. "Vaccines help keep our children and teens healthy and in the classroom."
Historically, the CDC has published vaccination coverage data in its Morbidity and Mortality Weekly Report, accompanied by official commentary on trends and the importance of vaccinations. However, since the current administration took office, the agency has posted data online with minimal accompanying statements. This year, a three-sentence statement from the CDC acknowledged the slight decline in kindergarten vaccination coverage and encouraged parents to "discuss vaccination options with their doctors."
Public health officials monitor kindergarten vaccination rates closely because schools can serve as hubs for germ transmission and potential outbreak epicenters. For years, these rates remained high, largely due to school attendance mandates requiring key vaccinations. All U.S. states and territories mandate vaccinations for diseases including measles, mumps, polio, tetanus, whooping cough, and chickenpox for children attending schools and childcare centers.
While all states permit medical exemptions for children with contraindications, most also allow exemptions for religious or other nonmedical reasons. The percentage of kindergartners with medical exemptions has remained stable at approximately 0.2% over the past decade, while nonmedical exemptions have increased.
Data from the CDC indicated that 17.5% of kindergartners in Idaho had an exemption for at least one vaccine in the last school year, a stark contrast to Connecticut, where fewer than 0.5% had exemptions.