As of early October 2026, the CDC has confirmed nearly 3,900 measles cases nationwide, already surpassing the full-year 2025 total of 2,289 and marking the highest annual count since 1991. This surge stems from 42 ongoing outbreaks—95% of cases are outbreak-associated and 95% occur in unvaccinated or unknown-status individuals—concentrated in states including Pennsylvania (approaching 1,000 cases), South Carolina, and Utah amid record kindergarten MMR exemptions. Sustained domestic transmission, rather than imports, reflects clustered under-vaccination and the virus's high contagiousness. Weekly CDC updates through year-end, plus any revisions to case or death counts, remain key data points for market resolution on total 2026 confirmed cases.