U.S. Measles Cases Exceed 4,000 in 2026, Marking Worst Outbreak Since 1991

The Centers for Disease Control and Prevention (CDC) reports that the United States has surpassed 4,000 measles cases in 2026, with 4,080 confirmed cases as of October 8. This marks the worst outbreak since 1991, with Pennsylvania alone accounting for over 1,100 cases and five measles-related deaths. Health officials attribute the surge to low vaccination rates and warn that the U.S. could lose its measles-free status.