Measles has reached the Lehigh Valley for the first time in recent memory, with St. Luke’s University Health Network confirming earlier this week it is treating two pediatric patients as Pennsylvania’s statewide case count climbs to its highest level in 30 years.

Pennsylvania has now reported 202 confirmed cases of measles this year as of Wednesday, including two in Lehigh County. Thirty-four people have been hospitalized.

“Measles cases in the state of Pennsylvania are on the rise. We saw this happening throughout the country, but now it’s right here in our backyard,” Dr. Jennifer Janco, chair of St. Luke’s Pediatric Department, said.

Nationally, 2,371 confirmed measles cases have been reported in the United States as of July 30, according to the U.S. Centers for Disease Control and Prevention. There have been 37 new outbreaks reported in 2026, and 94% of confirmed cases are outbreak-associated.

For the full year of 2025, the CDC recorded 2,289 confirmed cases.

A growing outbreak centered in Lancaster County has been at the center of two separate outbreaks this year, with 108 cases reported since April.

Measles is among the most contagious diseases known to medical science, capable of spreading without direct contact with an infected person.

“You only need to be around the airspace, not the person, and it can linger in the air. Nine out of 10 people who aren’t protected are going to contract measles if they’re exposed,” Janco said.

The virus can live for up to two hours in an airspace after an infected person leaves an area, according to the Pennsylvania Department of Health. A person with measles can spread the virus to others starting four days before through four days after the rash appears.

The consequences of infection can extend far beyond a temporary illness.

“Measles can make you sick enough to be in the hospital, affecting swelling of the brain and affecting the lungs,” Janco said. “It can absolutely cause a lifetime of complications.”

Despite the severity of the disease, Janco emphasized that vaccinated individuals have not been among those infected.

“We are seeing cases in children, but we have a very powerful prevention tool in the form of vaccination. We are not seeing cases of measles in vaccinated persons,” she said.

Two doses of the MMR vaccine are 97% effective at preventing measles, according to the CDC, while one dose provides 93% protection. Of the first 23 cases confirmed in Pennsylvania this year, 22 were unvaccinated and one had an unverifiable vaccination status, underscoring that vaccination remains the most effective protection, the state Department of Health said.

Nationally, vaccination coverage among kindergartners has decreased from 95.2% during the 2019-2020 school year to 92.5% in the 2024-2025 school year, leaving approximately 286,000 kindergartners at risk, according to the CDC.

In Pennsylvania, nearly 94% of kindergarten students during the 2024-2025 school year had received two doses of the MMR vaccine.

Janco urged parents with unvaccinated children to contact their pediatrician immediately. She also noted that some adults may have gaps in their protection they are unaware of.

“People born between 1963 and 1967 may have had an older version of the vaccine and might benefit from today’s updated version. And if you were vaccinated before 1991, you may have only received one dose because that’s what the recommendation was then,” Janco said.

Measles symptoms typically appear seven to 14 days after exposure, though the incubation period can last as long as 21 days. Common symptoms include high fever, cough, runny nose, red watery eyes and a rash, according to the Pennsylvania Department of Health.

Residents with questions about their vaccination status are encouraged to contact their primary care provider.

Additional information is available through the Pennsylvania Department of Health at pa.gov/health and the CDC at cdc.gov/measles.