The United States' measles outbreak has grown into the worst in more than three decades, with the Centers for Disease Control and Prevention reporting 2,777 confirmed cases so far in 2026 as of Aug. 20 — already surpassing the 2,289 cases recorded in all of 2025 and the highest annual total since the disease was declared eliminated domestically in 2000.
The cases span 47 states and jurisdictions and are linked to 36 separate outbreaks, according to CDC surveillance data, with outbreak-linked infections accounting for 94 percent of the total. Ninety-three percent of patients were unvaccinated or had unknown vaccination status, the agency said, and only 16 of the cases were tied to international travel — meaning the rest spread through local transmission after arriving in the country.
Earlier tallies in July put the national count at 2,318, with Utah's outbreak — more than 500 cases — the largest single cluster, followed by clusters of well over 100 cases each in Pennsylvania, Virginia and Arizona, according to reporting compiled by the University of Minnesota's CIDRAP project. Roughly 7 percent of patients this year have required hospitalization, down from 11 percent in 2025, and no deaths have been reported in 2026 after three fatalities the year before.
A Widening Gap in Childhood Vaccination
Public health officials trace the surge to falling kindergarten vaccination rates, which have slid from 95.2 percent nationally in the 2019–2020 school year to 92.4 percent last school year — below the roughly 95 percent threshold epidemiologists say is needed to sustain herd immunity against a disease as contagious as measles. The CDC and outside pediatric groups have continued to press the two-dose MMR vaccine, which is about 97 percent effective, as outbreaks have persisted continuously since January 2025.
After keeping measles under control for decades, the country has now experienced continuous outbreaks since January 2025.
Dr. Andrew Racine, President, American Academy of Pediatrics
The extended run of transmission puts the U.S. at risk of losing the measles elimination status the World Health Organization certified in 2000, a designation that requires a country go 12 consecutive months without sustained local spread. Health officials in the hardest-hit states say containment efforts are complicated by pockets of low vaccine uptake and, in some outbreaks, by delayed reporting as cases move through under-vaccinated communities. The CDC has said it will continue to update its national case count weekly as outbreaks in Utah, Pennsylvania and Arizona remain active heading into the fall school term.
