As of mid-June 2026, CDC surveillance reports 2,073 confirmed U.S. measles cases year-to-date—already nearing the full-year 2025 total of 2,288—with 93% tied to outbreaks across 40 jurisdictions and only 10 imported among international visitors. Sustained transmission stems primarily from undervaccinated clusters where MMR coverage falls below the 95% herd-immunity threshold, compounded by travel-related introductions into susceptible communities. Weekly case additions have moderated from earlier peaks, yet 6% hospitalization rates and ongoing multi-state activity keep totals climbing. CDC data releases every few days, plus state health department updates, provide the key near-term signals that could shift trader assessments of whether 2026 will set a new post-elimination record.