US Kindergarten MMR Vaccination Rate Dips as Non-Medical Exemptions Hit Record High

The CDC's latest national kindergarten vaccination data, released in August 2026, shows the share of US kindergarteners vaccinated against measles, mumps, and rubella (MMR) fell to 92.4%, a 0.1% decline from the prior school year. The release came roughly one week after Donald Trump made misleading claims about vaccines. (The Guardian)

Non-medical exemptions — parents opting out of vaccines for reasons other than health — rose 17% over the last school year, from 3.6% to 4.2% nationwide. That is the highest single-year increase ever recorded. The CDC's SchoolVaxView data page confirms that during the 2025-2026 school year, exemptions from one or more vaccines among kindergartners in the United States increased to 4.2% from 3.6% the previous year. (CDC SchoolVaxView)

Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia, said at least 280,000 US kindergarteners did not receive the MMR vaccine. He noted that immunization rates decreased in more than half of US states compared with the prior year and decreased across all vaccines. (The Guardian)

The data lands amid the worst US measles year since 1991, with hundreds of cases reported in Utah and South Carolina. The World Health Organization has credited widespread measles vaccination with saving 59 million lives globally between 2000 and 2024. (The Guardian; WHO)

Not every jurisdiction moved in the same direction. Dr. David Margolius, director of the Cleveland Department of Public Health, said the share of Cleveland kindergartners up-to-date on vaccines rose from 68% to 76%. That local improvement, however, runs against the national grain.

Historical CDC data provides context for the exemption trend. A CDC MMWR report on the 2017-18 school year found 4.2% of US kindergarteners had philosophical exemptions and 4.7% had any exemptions from vaccines. A CDC analysis of the 2012 and 2014 National Parental Surveys found 5.5% of parents reported intentionally delaying one or more childhood vaccines and 5.4% reported refusing one or more. (CDC MMWR; CDC analysis)

The public health stakes of under-vaccination are well documented in the agency's own records. The CDC reported that unvaccinated preschoolers aged 16 months to 4 years accounted for 44.7% of total preventable measles cases in the United States in 1986. (CDC MMWR)

The 92.4% MMR coverage figure sits below the 95% threshold generally cited for maintaining herd immunity against measles. Herd immunity is the level of vaccination in a population high enough to keep a disease from spreading — and measles is an especially difficult bar to clear, because the virus is so contagious. In epidemiology, R0 (pronounced "R-naught") measures how many people one infected person will pass the disease to in a susceptible population. Measles has an R0 of 12-18, meaning each infected person can infect up to 18 others if nobody is protected.

The broader context here is what a 0.1% decline means against an already low baseline. When coverage is already below the herd immunity threshold, any further drop widens the pool of people vulnerable to infection. The 280,000 kindergarteners lacking MMR vaccination that Dr. Offit cited is a substantial group for outbreaks to take hold in, especially in states where exemptions are clustered together.

The 17% jump in non-medical exemptions is the more consequential data point. A single-year shift of that magnitude suggests a change in behavior or policy rather than gradual drift. State-level exemption rules vary widely, from strict medical-only policies to broad personal-belief provisions. The CDC's finding that rates fell in more than half of states indicates the decline is geographically distributed rather than confined to a few outlier jurisdictions. The concurrent measles outbreaks in Utah and South Carolina, occurring during the worst national year since 1991, fit the epidemiological expectation that coverage declines precede outbreak activity.

Cleveland's improvement from 68% to 76% coverage shows that local intervention can move the needle even as national figures decline. Whether that kind of municipal-level effort can scale, or sustain, against the backdrop of rising exemptions and high-profile vaccine misinformation remains an open question for public health officials entering the 2026-2027 school year.