Vaccine exemptions for U.S. schoolchildren have climbed to a record high, and coverage rates for the measles, mumps, and rubella (MMR) vaccine among kindergartners have dropped below the federal target, according to new data from the Centers for Disease Control and Prevention. The figures represent a continuation of a multi-year decline in childhood immunization rates at the start of the school year.

The CDC data show that both medical and non-medical exemptions — including personal and religious exemptions — have increased, with non-medical exemptions driving much of the growth. At the same time, overall school vaccination rates have inched downward for another consecutive year, compounding concerns that began during the COVID-19 pandemic when routine childhood immunizations were disrupted.

Public health experts warn that falling MMR coverage threatens the herd immunity threshold needed to prevent measles outbreaks. Measles is among the most contagious infectious diseases known, and sustained community protection generally requires vaccination rates of 95 percent or higher. Current kindergarten coverage has fallen short of that benchmark nationally, though rates vary significantly by state.

The rise in exemptions reflects a broader shift in parental attitudes toward routine childhood vaccination that accelerated in recent years. Some states have relatively permissive exemption laws that make it easier for families to opt out, while others have moved to tighten requirements following previous measles outbreaks. The new data are likely to renew debate in state legislatures over exemption policies heading into the upcoming school year.