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U.S. measles cases surpass 2025 total, worst year since 1991

scienceJul 24, 202623492

The U.S. Centers for Disease Control and Prevention reported 2,318 measles cases as of Thursday, surpassing the full-year total of 2,289 in 2025 and making 2026 the worst U.S. measles year since 1991. Major outbreaks in South Carolina, Utah and along the Utah-Arizona border have driven the rise, with South Carolina recording 997 cases and Utah reporting more than 700 cases during its outbreak. State and academic analysts say official counts are incomplete; Utah state epidemiologist Dr. Leisha Nolen and modelers estimate the Utah-Arizona outbreak could be three to four times larger than known. Public health officials cite falling vaccination coverage as a key factor, with MMR kindergarten rates down to 92.5 percent in 2024-25 from 95.2 percent in 2019-20. Researchers including Damon Toth and Rémy Pasco highlighted data gaps and undercounts in multiple states, and Texas analysis suggests its 2025 outbreak may have been nearly twice the 762 confirmed cases. International health officials will meet in November to consider whether the U.S. and Mexico have lost their measles-free status, a formal consequence of rising domestic transmission.

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