Kindergarten measles vaccination coverage in the United States now ranges from 98.9 percent in West Virginia to 75.2 percent in Idaho, a 23.7-percentage-point spread between the highest and lowest states, according to figures the Centers for Disease Control and Prevention released on August 17 for the 2025 to 2026 school year.
Those two states also sit at opposite ends of American exemption law. West Virginia's statute allows only medical exemptions. Idaho allows a parent to exempt a child by submitting a signed statement citing religious or other grounds, with no requirement to provide further explanation.
For a parent, the useful question is not which state is doing better. It is what the rules actually are at your child's school, because school entry requirements are set by states rather than the federal government, and they differ more than most families assume. The national average tells you almost nothing about a specific classroom.
The Strictest Statute in the Country, Under Active Litigation
West Virginia Code 16-3-4 requires children to be immunized against a list of diseases before attending school and provides only a medical exemption. It is one of a small number of state laws with no religious or philosophical opt-out, and that framework has been contested continuously for the past two years.
Governor Patrick Morrissey issued Executive Order 7-25 on his second day in office, directing state health officials to create a religious exemption process based on the state's Equal Protection for Religion Act of 2023. In June 2025, the state Board of Education voted to direct county boards to follow the vaccine law as written, which does not include religious exemptions. Legislation to codify religious exemptions failed in the 2025 session, and lawmakers did not pass an exemption bill in 2026.
Raleigh County Circuit Judge Michael Froble issued a permanent injunction in late November 2025 requiring the boards to accept religious exemptions and certified the case as a class action. The West Virginia Supreme Court of Appeals granted a stay days later, and the board reinstated its policy. The appeal, covered in detail by West Virginia Watch, was briefed through the first half of this year, and no decision has been reported.
A separate federal case moved in the opposite direction. In April, a divided panel of the Fourth Circuit reversed a lower court order that had allowed an unvaccinated student to attend a public virtual school pending a religious exemption claim and sent the case back for further proceedings. As the federal appeals court sided with school officials, the practical situation for families stayed the same: the state health department has processed religious exemption certificates while public schools have been directed not to accept them.
Idaho Requires Only a Signed Statement
Idaho's approach is structurally different. Under Idaho Code 39-4801, rewritten in 2025 to consolidate the state's exemption provisions, a parent or guardian may exempt a child from any or all required immunizations by submitting a signed statement objecting on religious or other grounds. A medical exemption requires certification from a licensed clinician, but the non-medical route does not require a reason to be specified or reviewed.
State law also directs schools and daycare facilities to describe the available exemptions and cite the statute in any communication to parents about immunization. Children who are in the process of catching up may be conditionally enrolled, according to the state health department's school and daycare page. Idaho also reported the country's highest kindergarten exemption rate for the latest school year, at 17.5 percent.
In 2025, Governor Brad Little signed Senate Bill 1210, the Idaho Medical Freedom Act, which took effect that July and prohibits schools, daycares, government entities, and most businesses in the state from requiring a medical intervention, including a vaccine, as a condition of attendance or employment. As enacted, the law is subject to existing provisions that allow school trustees to exclude students who have, or are suspected of having, a contagious disease.
An Association: The Data Cannot Turn into a Cause
The national picture from the same CDC release is that exemptions among kindergartners rose to 4.2 percent from 3.6 percent; exemptions increased in 41 states and the District of Columbia, 24 states now report exemption rates above 5 percent, and roughly 280,000 kindergartners attended school without documentation of completing the two-dose measles, mumps, and rubella series. MedicalDaily reported on the record exemption figures when they were published.
The association between permissive exemption law and lower coverage is visible in these two states. The data do not establish how much of the 23.7-point gap is attributable to statute. Coverage figures also reflect record-keeping practices, provider availability, population distribution, the share of children who are simply undocumented rather than exempt, and differences in how states collect and report the data, a limitation the CDC notes on its own SchoolVaxView page. Two states can differ for reasons unrelated to either legislature.
Mississippi complicates any simple reading further. It long led the country on childhood vaccination under one of the strictest statutes, began accepting religious exemptions after a federal court ordered it to in 2023, and still ranks among the states with the highest kindergarten MMR coverage. Law is one input among several, and the states that sit at the extremes are not a controlled experiment.
It is also worth separating two categories that get conflated. About 155,000 kindergartners were exempt from one or more vaccines, a count that covers families who filed paperwork. The roughly 280,000 without documentation of a completed MMR series is a larger number that includes incomplete records. They are not the same population.
Practical Checks Before the School Year Starts
Families should confirm what their child's school actually has on file rather than relying on memory, since enrollment and exclusion decisions are made from documentation. Most states operate an immunization information system that allows parents to request a copy of their child's immunization record. MedicalDaily has published a guide to finding an MMR record and catching up on a missed dose.
Households moving between states should check the destination state's health department page rather than assuming rules carry over. Requirements, accepted documentation, grace periods, and exemption categories all vary.
Cost is generally not the barrier it appears to be. The federal Vaccines for Children program covers recommended vaccines at no cost for children through age 18 who are Medicaid-eligible, uninsured, underinsured, or American Indian or Alaska Native, and most private plans cover routine childhood immunizations without cost-sharing.
The West Virginia Supreme Court has not issued a decision, and Idaho lawmakers have continued to introduce bills that would further loosen school immunization requirements. Both are worth watching, and MedicalDaily will report the outcomes as they arrive.
Key Questions Answered
Which states are highest and lowest in kindergarten MMR coverage? West Virginia at 98.9 percent and Idaho at 75.2 percent, according to CDC figures for the 2025 to 2026 school year.
Does West Virginia allow religious exemptions? State law provides only medical exemptions. A governor's executive order created a religious exemption process, the state Board of Education directed schools not to accept those certificates, and the dispute is before the state Supreme Court.
How does a parent claim an exemption in Idaho? By submitting a signed statement to school officials objecting on religious or other grounds. No explanation or review is required for the non-medical route.
Does exemption law explain the gap between the two states? It is one visible difference, but the data cannot show how much of the 23.7-point gap it accounts for. Record-keeping, access, and reporting methods also vary by state.
What is the national exemption rate now? 4.2 percent, up from 3.6 percent, covering about 155,000 kindergartners, with 24 states reporting rates above 5 percent.
Are school vaccine rules set federally? No. States set school entry requirements, which is why documentation, grace periods, and exemption categories differ across state lines.
Where can families get vaccines at no cost? Through the federal Vaccines for Children program for eligible children through age 18, and through most private insurance without cost sharing.
