Measles vaccine rates of children fall in most counties, study shows
Measles vaccination rates among U.S. children have dropped in recent years, falling below the “herd immunity” threshold needed to prevent outbreaks, according to a new Johns Hopkins study. National coverage declined from nearly 94% in 2018 to just over 91% in the most recent school year.
As health officials monitor the trend, the U.S. Centers for Disease Control and Prevention (CDC) has updated its travel guidance and now urges all international travelers to be vaccinated against measles, regardless of their destination.
Newly released study cites drop in vaccination rates
The study used county-level data from 33 states, relying on publicly available information. The study found that MMR (measles-mumps-rubella) vaccination rates dropped among school-aged children. According to the data, vaccination rates between the 2017-2018 school year were 93.92%. The rates dropped to 91.26% in the 2023-2024 school year.
Researchers found that measles vaccination rates varied widely by state and region. Among the more than 2,000 counties analyzed, the data showed a 78% difference between the highest and lowest coverage rates.
Despite a decline in certain areas, Maine, New York and California were among the states that had seen an increase across their counties when it came to vaccination rates.
CDC also cites a decrease in vaccinations among kids
Nationwide, measles vaccination coverage among kindergartners dropped from 95% in the 2019-2020 school year to 93% in the 2023-2024 school year. According to the CDC, this decline left about 280,000 children at risk.
CDC updates guidance amid more US cases, outbreaks
As outbreaks and cases rise in the U.S., the CDC is updating its guidance for international travelers. Its latest advisory suggests all Americans receive the MMR vaccine regardless of where they are headed. “All international travelers should be fully vaccinated against measles with the measles-mumps-rubella (MMR) vaccine,” the CDC said.
For international travel, the CDC recommends that infants aged 6 to 11 months receive one early dose of the measles vaccine. Anyone 12 months or older should get two doses at least 28 days apart, unless they have documented immunity.
The CDC classifies measles as a “level one” global threat, meaning travelers should practice usual precautions. However, the agency notes that cases are rising around the world. According to the CDC, most U.S. measles cases occur when unvaccinated travelers contract the virus abroad and bring it back into the country.
Current status of US cases
As of May 14, researchers say they documented more than 1,000 measles cases in the U.S. in 2025, most involving unvaccinated children. The study warns that if vaccination rates continue to decline, the country could experience a resurgence of measles as an epidemic.
The CDC currently reports there are 1,088 cases in 33 states, with 14 outbreaks in 2025 –– the highest since 2019. Most of the cases are in Texas, New Mexico and Kansas.
Of the reported cases, 322 involve children under 5 years old, while 407 are between the ages of 5 and 19. CDC data shows three measles-related deaths have been confirmed in the U.S. this year.
Ella Rae Greene, Editor In Chief
