As of early May 2026, the CDC has confirmed 1,842 measles cases in the United States, on pace to exceed 2025’s full-year total of 2,288, with 93% tied to ongoing outbreaks across 36 states. This resurgence stems from sustained declines in MMR vaccination coverage, leaving clusters of unvaccinated children and adolescents vulnerable to highly transmissible airborne spread from imported cases. Official data show 72% of 2026 infections occurring in those under 20, with most linked to domestic outbreaks rather than travel alone. Weekly CDC surveillance updates on new case counts, outbreak expansions, and vaccination status distributions will continue to shape trader assessments of whether the year-end total surpasses or falls short of recent highs.