Childhood Vaccination Data: New 2026 Report Methodology
Researchers analyzed state records to track MMR rates and exemptions for kindergarteners, noting that nearly 40% of counties saw drops of over five percentage points since 2019.
By Robert Ward ·
Researchers at Stanford University and data analysts have finished a new investigation into childhood vaccination rates across the United States. The project, an update to a 2025 study, examines data collected between June and October 2026. The goal is to map how many kindergarteners are receiving required vaccines and how many are using exemptions to skip them.
The team built a database using records from state health agencies. They standardized the information to allow for comparison across thousands of counties. The analysis focuses on four specific areas. First, it tracks medical exemptions, which are granted when a condition makes vaccination potentially harmful. Second, it counts nonmedical exemptions based on personal or religious beliefs. Third, it measures MMR vaccination rates, specifically counting the second dose where available. Fourth, it determines how many students are up to date with the full series required for school enrollment.
Processing the data required extensive manual work because states use different formats. Some states, including Ohio and New York, required additional calculations to aggregate the supplied figures. Other states forced analysts to hand-enter hundreds of rows of tabular data. Every entry was checked for accuracy to manage inconsistencies in the original records.
The results show a clear trend in MMR coverage. Almost four in 10 counties experienced a decline of more than five percentage points in vaccination rates since 2019. Approximately one in eight counties saw a drop of that magnitude since 2024. Fewer than 2% of counties recorded a decline of 0.1 percentage points or less over the same long-term period.
Variations in how states collect data present several challenges. Florida stopped providing kindergarten exemption data after the 2021-2022 school year. Montana ceased collecting the data after 2019, a change linked to a state bill passed in 2021. Some states, such as Arizona and Minnesota, do not track an overall up-to-date figure. Others, including Mississippi and West Virginia, provide data for all K-12 grades rather than just kindergarteners.
Several states did not provide county-level data. Delaware and Rhode Island used state-level figures instead. Indiana could not provide county-level exemption data. West Virginia began providing county-level exemption data only in January 2025. Wyoming used data for 19- to 35-month-olds because its kindergarten reporting was inconsistent. Alaska provided regional data but withheld specific exemption details due to small sample sizes.
