An increase of 178 confirmed cases in the latest U.S. weekly update lifted the 2026 measles total above twice last year’s count, according to federal health data.
The Centers for Disease Control and Prevention (CDC) reported 4,588 cases through Oct. 22, 178 more than the previous weekly tally. That earlier update counted 4,410 cases through Oct. 15. This year’s total is 10 higher than twice the 2,289 cases recorded for all of 2025.
The CDC’s breakdown included 4,570 cases reported by 47 jurisdictions and 18 among international visitors. Outbreaks were associated with 4,404 cases, or 96% of the total. The agency reported 43 new outbreaks in 2026.
Cases linked to outbreaks that began in 2026 totaled 3,020, while 1,384 were connected to outbreaks that started in 2025. Under the CDC’s definition, an outbreak requires at least three related cases.
The Pennsylvania Department of Health counted 1,338 cases across 44 counties as of Oct. 23, including 255 hospitalizations and five confirmed measles-associated deaths. The CDC’s national dashboard listed three deaths in its Oct. 23 update and said the count could change. The agency is working with the Council of State and Territorial Epidemiologists on a standardized definition for measles deaths.
Pennsylvania also reported that pop-up clinics had administered more than 6,500 vaccinations since the outbreak began in late April. Four of the state’s reported cases were among vaccinated people, less than 1% of its total.
Measles, mumps and rubella (MMR) vaccination coverage among U.S. kindergartners fell to 92.4% in the 2025-26 school year from 95.2% in 2019-20. The CDC estimated about 280,000 kindergartners were at risk in 2025-26. It says local coverage above 95% can help community immunity protect most people.
The CDC cites declining vaccination coverage, communities with lower rates and rising measles activity abroad as factors in the increase. Measles was declared eliminated in the United States in 2000.
