US measles cases in 2026 more than double 2025 total

The US has recorded 4,588 measles cases as of October 22, 2026, more than double the 2,289 cases reported in all of 2025, according to the CDC. Pennsylvania has reported the highest number, with at least 1,338 cases, NPR reported. The CDC recommends that adults have documentation of at least one dose of the measles, mumps and rubella (MMR) vaccine.