Kindergarten vaccination rates in the U.S. continued to decline in the 2025-2026 school year, with the percentage of children receiving exemptions reaching an all-time high, according to federal data. 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 of record-high exemption rates, with the majority of these being for nonmedical reasons. Exemptions saw an increase in 41 states and the District of Columbia.
The Centers for Disease Control and Prevention (CDC) reported that 92.4% of kindergarteners 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 disease clusters or outbreaks. Rates also fell for polio, the combination vaccine for diphtheria, tetanus, and pertussis, and the first dose of the chickenpox vaccine. The rate for the hepatitis B vaccine remained steady, though changes to infant hepatitis B vaccine recommendations may not be reflected in kindergartner data for several years.
These declining vaccination numbers coincide with the U.S. experiencing its most severe measles year since 1991. Experts estimate that over a quarter-million children entering kindergarten are now susceptible to measles. These at-risk children are not uniformly distributed, with higher concentrations of unvaccinated children in certain areas contributing to localized measles outbreaks.
Experts suggest that recent shifts in federal health guidance have contributed to confusion. U.S. Health Secretary Robert F. Kennedy Jr., who previously advocated against vaccines, has been involved in efforts to revise and reduce childhood vaccination recommendations. President Donald Trump has also called for changes to childhood vaccination schedules, promoting the idea of spacing out shots over multiple 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 current vaccination numbers indicate a significant portion of kindergartners are susceptible to measles.
Public health officials typically emphasize the importance of vaccines, especially as the school year begins. All U.S. states and territories mandate vaccinations for children attending childcare centers and schools, covering diseases like measles, mumps, polio, tetanus, whooping cough, and chickenpox. While all states permit medical exemptions, most also allow for religious or other nonmedical exemptions. For the past decade, medical exemption rates have remained stable at approximately 0.2%, while nonmedical exemptions have steadily increased. The data showed significant variation by state, with Idaho reporting 17.5% of kindergartners having an exemption to at least one vaccine, compared to fewer than 0.5% in Connecticut.