The United States reports record-high measles cases this year, driven by declining immunisation coverage and outbreaks in low-vax communities, as health officials ramp up response efforts.
The United States has recorded 3,659 confirmed measles cases so far this year, according to the latest data from the Centers for Disease Control and Prevention, up from 3,471 a week earlier. That represents 188 additional cases and a 5.4% weekly increase, underscoring how quickly the virus continues to spread across the country as autumn approaches. The CDC said the cases have been reported in 47 jurisdictions, with 17 infections identified in international visitors. It also said 95% of confirmed cases are linked to outbreaks, including clusters that began in both 2025 and 2026.
Pennsylvania remains one of the hardest-hit states. The Pennsylvania Department of Health reported 835 cases across 39 counties as of 23 September, an increase of 104 cases in a week. The state has also recorded 164 hospitalisations and four measles-associated deaths. In a separate update issued earlier in September, the department said it had counted 693 cases across 38 counties, and that it was investigating a possible measles-related death in Jefferson County. Health officials have responded with vaccination efforts, including nearly 5,200 MMR shots delivered at 156 pop-up clinics since the outbreak began in late April, while state staff have given more than 7,700 doses in total this year.
The outbreak has hit communities with low vaccination rates particularly hard. A report by MS NOW described widespread transmission in Lancaster County’s Amish community, where many residents are unvaccinated and therefore more vulnerable to infection. The same report said one infectious-disease doctor in Danville had treated well over 90 measles patients this year. Pennsylvania officials have repeatedly urged residents to seek vaccination, saying the MMR shot is the best protection against the virus and is about 97% effective after two doses.
National immunisation coverage helps explain why the current outbreak is proving so difficult to contain. CDC data show that MMR vaccination among US kindergartners has slipped from 95.2% in the 2019-20 school year to 92.4% in 2025-26, leaving more children exposed to infection. Only 10 states are now above the 95% threshold needed for community protection, according to the federal agency. With three months still left in 2026, the country has already surpassed every full-year measles total recorded since elimination was declared in 2000, overtaking even the previous peak of 1,274 cases in 2019 and the 2,289 cases logged in all of 2025.
Disclaimer: This content is for informational purposes only and is not intended to be a substitute for professional medical judgment, advice, diagnosis, or treatment.
