U.S. MMR Vaccination Trends

We collected county-level two-dose MMR vaccination rates for kindergarteners from each state’s department of health website from 2017 to 2024, where available. The dataset includes at least one year of vaccination data for 2,237 counties across 38 states. The county-level vaccination data complements the state and national-level from the Centers for Disease Control and Prevention, confirming a widespread decline in MMR vaccination rates in the U.S. following the COVID-19 pandemic, while also revealing the significant heterogeneity of vaccination patterns within and across states. Out of 2,066 counties studies, 1,614 counties, or 78%, reported drops in vaccinations. The average county-level vaccination rate fell from 93.92% pre-pandemic to 91.26% post-pandemic—an average decline of 2.67%, moving further away from the 95% herd immunity threshold to predict or limit the spread of measles. The data was published June 2 in JAMA .