Sustained measles transmission driven by vaccination gaps below the 95% herd immunity threshold continues to fuel record U.S. case counts in 2026. As of August 13, the CDC reports 2,566 confirmed cases—already exceeding the full-year 2025 total of 2,289 and marking the highest annual figure since 1991—with 38 new outbreaks and 94% of infections outbreak-associated across 47 jurisdictions. Most cases involve unvaccinated individuals, including 20% under age 5, reflecting imported introductions and local chains in under-immunized communities. CDC weekly updates and state surveillance reports will shape trader views on whether totals remain elevated through year-end, while any Pan American Health Organization review of elimination status could highlight ongoing risks from declining routine MMR coverage.