Measles cases in the United States have reached a 35-year high, with 4,080 confirmed cases reported as of Oct. 8, surpassing the 2,289 cases recorded throughout 2025, according to the Centers for Disease Control and Prevention.
Pennsylvania has reported 1,078 measles cases statewide as of Oct. 7, compared with 16 during all of 2025, according to the Pennsylvania Department of Health, as officials contend with an ongoing outbreak. Other states have also battled significant outbreaks.
South Carolina experienced an outbreak totaling 997 cases between October 2025 and March 2026 before it was declared over in April, according to state health officials. The Utah Department of Health and Human Services has reported more than 500 cases this year. New York Gov. Kathy Hochul declared a disaster emergency in October in response to rising infections.
Missouri has reported 11 confirmed measles cases this year, including one involving a St. Louis County resident, according to the Missouri Department of Health and Senior Services. No city of St. Louis residents are listed among the confirmed cases, although state and local health officials issued warnings in September about possible exposures at Busch Stadium and several other locations in the region.
Despite the relatively low number of cases, Missouri’s preliminary school-reported vaccination rate for measles, mumps and rubella (MMR) is 89.5%, according to the state health department. That is below the approximately 95% coverage the CDC says is generally needed to prevent sustained measles transmission.
The United States is at risk of losing its measles elimination status, achieved in 2000, according to the CDC. The World Health Organization defines elimination as the absence of continuous, locally established transmission for at least 12 months. The CDC has described achieving that status as a “historic public health achievement.”
The CDC reports that the overwhelming majority of measles cases involve people who are unvaccinated or whose vaccination status is unknown. Health and Human Services Secretary Robert F. Kennedy Jr. has a long public record of skepticism toward certain vaccines and public health mandates.
The American Academy of Pediatrics has linked the resurgence of measles to declining vaccination rates for the MMR vaccine.
According to the CDC, two doses of the MMR vaccine are approximately 97% effective against measles. The vaccine is typically administered to children at ages 12 to 15 months for the first dose and ages 4 to 6 years for the second. CDC data show that MMR vaccination coverage among U.S. kindergartners fell from 95.2% in the 2019-20 school year to 92.4% in 2025-26, below the level generally needed to prevent sustained transmission.
Kennedy’s criticism of vaccine programs has also raised concerns among public health organizations about the federal government’s messaging on routine immunizations.
Sylvester Brown Jr. is the Deaconess Foundation Community Advocacy Fellow.