Pennsylvania Measles Outbreak Passes 1,066 Cases, Largest Since 2000

Pennsylvania has recorded 1,066 outbreak-linked measles cases since April, making it the largest U.S. measles outbreak since the disease was declared eliminated in the country in 2000, according to Ars Technica, which cited state health department data reported Wednesday.

State health officials put the full 2026 case count at 1,078, which includes 12 cases logged in January and March before the current outbreak began. The remaining 1,066 cases have accumulated since April. Officials reported 145 new cases in the past seven days and 74 since the previous update on Monday, though 40 of those were infections identified more than two weeks ago that are only now being added to the tally, Ars Technica reported.

How many people have been hospitalized or died?

The outbreak has resulted in 207 hospitalizations and five deaths, according to the report. The deaths include a newborn, a 6-week-old infant, an 18-year-old, a 20-year-old and a 40-year-old. All five were unvaccinated; the two infants were too young to have received the measles vaccine. Every death occurred during the current outbreak.

How does this compare with past U.S. outbreaks?

Pennsylvania's case count now exceeds the two largest recent U.S. outbreaks by wide margins. A Texas outbreak that ran from January to August 2025 ended at 762 cases. An outbreak in South Carolina that ended in April had 997 cases, which had been the prior record holder, according to Ars Technica. Pennsylvania's 1,066 outbreak-linked cases surpass both.

The only larger measles outbreak in recent U.S. history was in New York from 1990 to 1991, which infected more than 4,500 people, the outlet reported. With 34 new infections reported since Monday, the Pennsylvania outbreak shows no clear sign of ending.

Nationally, the Centers for Disease Control and Prevention is reporting 3,887 measles cases for the year, the highest annual total since 1991, when the U.S. recorded 9,643 cases, according to Ars Technica.

Has the U.S. lost its measles elimination status?

Measles was declared eliminated in the United States in 2000 after decades of vaccination campaigns. Elimination status requires vaccination rates high enough to prevent sustained transmission of the virus over a 12-month period, per the report.

In November, experts at the Pan American Health Organization, which serves as a regional World Health Organization office, will review U.S. data to determine whether the country has lost that status. Ars Technica reported that experts widely expect the U.S. will be found to have lost its elimination status. Canada lost its own measles elimination status in 2025.

What are other states doing about rising case counts?

New York Governor Kathy Hochul this week declared a State Disaster Emergency over rising measles cases in her state, where at least 108 cases have been reported, according to Ars Technica. The declaration expands the pool of health workers authorized to administer measles vaccines to include paramedics, advanced EMS providers, pharmacists and midwives. It also allows nurses, not just physicians, to order measles tests.

"No one should get seriously ill or die from a vaccine-preventable disease," Hochul said in a statement cited by the outlet. "That is why I have taken steps to increase the number of health professionals who can vaccinate and test."

Why are measles outbreaks increasing nationwide?

Ars Technica linked the resurgence to slipping vaccination rates nationwide, which have allowed measles — among the most contagious viruses known — to spread more easily once introduced into unvaccinated communities. The outlet reported that outbreaks and case counts have climbed over the past several years as vaccination coverage has eroded in parts of the country.

The five deaths tied to the Pennsylvania outbreak occurred exclusively among unvaccinated individuals, underscoring the role vaccination status plays in outcomes once the virus begins circulating in a community, according to the report.

State and federal health officials continue to track new cases as they are confirmed, with Pennsylvania's count subject to revision as delayed reports — such as the 40 older cases added this week — are incorporated into the official tally. The scale of the outbreak, combined with the pending PAHO review, has placed renewed attention on vaccination coverage as a determinant of whether the virus can sustain transmission within U.S. borders going forward.