U.S. Faces Surge in Measles Cases with Pennsylvania Hit Hardest

The U.S. is facing its largest measles outbreak in decades, with Pennsylvania seeing significant numbers. Data from the Centers for Disease Control and Prevention (CDC) reveal over 4,580 measles cases nationwide since October 22, surpassing last year’s total of 2025 cases. Notably, 96% of those affected in 2026 were either unvaccinated or had unknown vaccination status.

As the outbreak intensifies in Pennsylvania, state health officials are emphasizing full vaccination. The Pennsylvania Department of Health reported a total of 1,338 confirmed measles cases across 44 counties this year, as of October 21. The outbreak led to more than 250 hospitalizations and five fatalities. Lancaster and Mifflin counties, heavily affected, particularly include Amish communities with low vaccination rates. Three of the deceased resided in Lancaster County.

Pennsylvania Secretary of Health Dr. Debra Bogen recently engaged in discussions with healthcare providers in Mifflin County to better understand their challenges. Dr. Bogen stressed the importance of communicating with those actively managing the outbreak to enhance the state’s public health response.

Vaccination remains the most effective preventive measure. The CDC states that two doses of the measles, mumps, and rubella (MMR) vaccine are approximately 97% effective against measles, while one dose offers about 93% protection. Interest in measles vaccination has grown, with over 39,000 vaccines administered in Pennsylvania in the first three weeks of October, up from the typical monthly average of 25,000.

The rise in cases is not confined to Pennsylvania. New York, facing its own increase, saw over 160 confirmed cases, prompting Governor Kathy Hochul to declare a disaster emergency. Meanwhile, Utah tallied over 700 cases, though none have been reported in the past three weeks. In South Carolina, a previous outbreak resulted in 997 cases before concluding in April.