The U.S. is in the midst of its worst measles outbreak in decades, with more than 4,000 cases reported to the Centers for Disease Control and Prevention as of early October and a sixth measles-associated death disclosed by local Pennsylvania officials on Monday.
The vaccine-preventable disease was declared eliminated in the U.S. back in 2000— meaning that there was no endemic spread of the disease—but has begun to resurface in force during recent years as declining childhood vaccination rates have pushed most states below the 95% coverage bar for school-age herd immunity.
The CDC had counted 2,289 cases across the entirety of 2025, which had been the country’s highest total since 1990, and several public health officials have warned for months that number would likely be surpassed based on the scale and frequency of early-year cases.
Measles-associated deaths has also accompanied the higher case counts, though just how many is a subject of dispute. While three deaths were confirmed in all of 2025, this year logged its first in late August with Pennsylvania, which hosts more than a quarter of the total cases, now reporting six measles-associated deaths as of Oct. 13. The CDC, however, lists two deaths alongside a note that its count is subject to change, and has promised more broadly to develop a new, standardized case definition to be used across all reporting states.
That discrepancy is an example of friction between federal health leadership and the broader public health community that experts say has contributed to this year’s outbreaks.
Pennsylvania’s initial death announcements in August were contested by Health and Human Services Secretary Robert F. Kennedy Jr., who accused Pennsylvania Governor Josh Shapiro of withholding sufficient information for the CDC to confirm the deaths and using his press conference announcing them as “gaslighting the public” for political purposes.
During an ensuing social media feud, the governor and the secretary described a heated phone call in which Shapiro (at the time) rejected federal assistance and accused Kennedy of fueling the outbreaks with only lukewarm endorsement of the MMR vaccine and a broader concurrent campaign to scale back other routine childhood vaccinations.
Numerous state public health officials and experts have lobbed similar criticisms of the Kennedy, who is affiliated with anti-vaccine groups, and federal health agencies under his purview.
The CDC, for its part, has reportedly infused at least $100 million of extra public health funding to states for immunization programs and surveillance, and leading officials including Kennedy and new CDC Director Erica Schwartz, M.D., have described the MMR vaccine as safe and effective when asked directly. Still, the agency has not launched the type of broader vaccine messaging and awareness campaigns that it would have in years past, critics are quick to note.
Pennsylvania isn’t alone in raising alarms over rising measles cases. New York Governor Kathy Hochul declared a State Disaster Emergency in early October, the first such declaration in recent years