MMR vaccination rates declined 78% since 2019, study finds

A JAMA study published June 3 found that of 2,237 counties across the U.S., 78% reported declines in vaccination rates for measles, mumps and rubella from 2019 through 2024. The study said that measles is likely to return to endemic levels in the U.S. if MMR vaccination rates continue to decline.  
 
The Centers for Disease Control and Prevention released guidance May 28 advising all international travelers to be vaccinated against measles. As of May 29, there have been 1,088 confirmed cases of measles in the U.S. this year, according to CDC data. There were 285 in 2024. So far in 2025, cases have been reported by 32 states. The vaccination status of 96% of all cases is classified as “unvaccinated or unknown.”