U.S. measles cases top 1991 levels as outbreaks spread across 35 states
More than 2,300 measles cases have been reported in the United States through mid-2026, surpassing the previous year’s record and marking the highest annual total since 1991.
The United States has recorded over 2,300 measles cases through the first five months of 2026, exceeding the 2,298 cases reported in 2025 and the highest number since 1991, according to the Centers for Disease Control and Prevention. The surge follows a period in which the disease, declared eliminated in 2000, saw more cases in the past 18 months than in the preceding 25 years combined.
Most infections involve children who are unvaccinated, and more than 90% of cases nationwide are linked to individuals with no documented measles-mumps-rubella (MMR) vaccination. Outbreaks have been reported in 35 states, with South Carolina experiencing the largest single outbreak of nearly 1,000 cases that began in Spartanburg County in October 2025 and continued into April 2026.
"This essentially is a public health failure, and it's avoidable," said Dr. Andrew Racine, president of the American Academy of Pediatrics.
Public health officials describe contact-tracing efforts as labor-intensive. In San Francisco, the health department indicated that handling more than one case simultaneously would require additional staff, a concern amplified by recent funding cuts. Similar challenges have been reported in Virginia, where a single outbreak in Buckingham County has produced more than 150 cases, prompting mobile vaccination clinics and community outreach.
Virginia health officials emphasized that high overall vaccination rates can mask local pockets of low coverage, which sustain transmission. In Pennsylvania’s Lancaster County, over 100 cases have been linked to unvaccinated individuals, leading to pop-up clinics that have administered hundreds of MMR doses.
Health departments across affected states are urging unvaccinated residents to avoid large gatherings and are coordinating mobile vaccination efforts to improve access. The ongoing outbreaks have raised questions about whether the United States can retain its measles-elimination status when reviewed by international health authorities later this year.