In the first six months of 2026, the number of measles cases recorded in the United States surpassed the 2025 total. Forty-seven jurisdictions reported 3,454 confirmed measles cases (as of September 17, 2026) to Centers for Disease Control and Prevention (CDC). At the end of 2025, the agency recorded 2,289 measles cases. CDC released the toolkit, Be Ready for Measles, to aid health care providers in communicating measles prevention and outbreak information to patients.