Pennsylvania’s explosive measles outbreak is now the largest the US has seen since the highly infectious virus was declared eliminated in 2000. With well over 1,000 cases, it’s the largest on record since 1991.

Pennsylvania’s health officials reported 1,078 measles cases in all of 2026 as of this afternoon. That includes 12 cases in January and March, with the remaining 1,066 cases since April, when the current outbreak began. The tally includes 145 cases recorded in the last seven days and 74 identified since the previous update on Monday. Health officials noted that 40 of the 74 cases added today were from more than two weeks ago and are just now being recorded.

Among the cases, there have been 207 hospitalizations and five deaths—a newborn, a 6-week-old, an 18-year-old, a 20-year-old, and a 40-year-old. All of the deaths occurred during the current outbreak in people who were unvaccinated; the two infants were too young to have been vaccinated.

With slipping vaccination rates nationwide, measles outbreaks and cases have come roaring back in the past few years. A large outbreak in Texas that spanned January­–August 2025 ended with 762 cases, while an outbreak in South Carolina ended in April with 997 cases, the previous record holder. Pennsylvania exceeds that handily with its 1,066 outbreak-linked cases as of today. With 34 new infections reported since Monday, the outbreak does not appear to be close to ending.

Measles emergency

Measles was declared eliminated in the US in 2000 after decades-long vaccination efforts. Elimination is earned and maintained with vaccination rates that prevent continuous transmission of the virus during a 12-month period. In November, experts at the Pan American Health Organization (PAHO)—which acts as a regional office for the World Health Organization—will review data on whether the US has lost its measles elimination status. Experts widely expect the US has lost the status. Canada lost its elimination status in 2025.