Measles, a highly contagious disease that was once considered eradicated in the United States, has seen a troubling resurgence in recent months.

Health officials have confirmed new cases in New Jersey and Pennsylvania, including a recent case in Montgomery County, marking the first reported instance of measles in Pennsylvania for 2025. Experts attribute these outbreaks to declining vaccination rates and increased international travel, raising concerns about the potential for further spread.

According to the Pennsylvania Department of Health, “there is no immediate risk to the general public at this time, as 94 percent of commonwealth residents are vaccinated against the measles virus.”

The Centers for Disease Control and Prevention reports that two doses of the measles, mumps and rubella vaccine are 97 percent effective against the virus. Despite those assurances, health professionals warn that pockets of under-vaccinated populations could still be vulnerable to outbreaks.

Dr. Jeffrey Jahre, an infectious disease specialist with St. Luke’s University Health Network, emphasized that the current rise in cases threatens the measles-free designation the U.S. has held since 2000.

“People tend to think about measles in the past tense,” Jahre said. “There is a general feeling that it’s not anything to worry about, but that is a mischaracterization. Measles was one of the most common causes of childhood deaths from viral disease before immunization.”

Jahre detailed the serious risks associated with measles, particularly among young children, pregnant individuals and those with compromised immune systems. “About one in five unvaccinated individuals who contract measles in the U.S. will be hospitalized,” he said. “One in 20 children with measles develop pneumonia, the leading cause of death from measles in young children. Additionally, 1 in 1,000 cases lead to encephalitis, which can cause permanent neurological damage, including seizures and intellectual disabilities.”

Beyond the immediate risks, Jahre noted a delayed but devastating complication known as subacute sclerosing panencephalitis.

“Even in children who seem to recover, SSPE can develop seven to 10 years later, leading to severe brain inflammation and death,” he said.

The current outbreaks have primarily been linked to unvaccinated individuals and international travel. In Texas, the state is experiencing its largest measles outbreak in 30 years, with 158 reported cases across nine counties. In Pennsylvania, the Montgomery County case involved a child under the age of 1 who was too young to be vaccinated and contracted the virus while traveling abroad.

Dr. Tibisay Villalobos, chief of the Department of Pediatrics, Section of Infectious Diseases at Lehigh Valley Health Network, pointed out that measles outbreaks typically begin with an unvaccinated traveler returning to a community where immunization rates are low.

“If the number of vaccinated individuals in a community is below what we consider protective, an outbreak will occur,” Villalobos said. “You need what we call community immunity to prevent the disease from spreading.”

Both St. Luke’s and Lehigh Valley Health Network have taken proactive steps to prepare for potential measles cases.

“We are not waiting for the situation to become critical,” Jahre said. “We have already updated our protocols and informed health care providers on how to recognize, test for, and handle suspected measles cases. We are emphasizing the need for isolation measures, as measles is one of the most contagious diseases known, with the virus remaining airborne for up to two hours after an infected person leaves a room.”

Villalobos echoed those concerns and stated that Lehigh Valley hospitals had already refreshed their recommendations following previous cases in Philadelphia.

“We have protocols in place for screening patients in pediatric practices and acute care settings,” she said. “We are prepared to identify and isolate cases to prevent further spread.”

Vaccine hesitancy remains a major challenge in combating measles outbreaks. According to Jahre, declining vaccination rates can be traced back to misinformation, particularly following the COVID-19 pandemic.

“Since COVID, we’ve seen an increase in vaccine distrust,” he said. “About 20 percent of the population now identifies as outright anti-vaccine, while others are hesitant or experiencing vaccine fatigue.”

Villalobos noted that vaccine rates in the Lehigh Valley have not fully returned to pre-pandemic levels.

“Immunization rates vary by school district and Zip code,” she said. “Allentown School District has one of the highest vaccination rates due to proactive efforts and school-based programs, but there are pockets in Northampton and Berks counties where rates are lower.”

In response to vaccine hesitancy, both health networks are engaging in community outreach efforts.

“St. Luke’s has taken a different approach than some other institutions,” Jahre said. “Some health care providers refuse to treat unvaccinated patients. We, however, accept all patients and work to educate them on the benefits of vaccination. We’ve found that with transparency and evidence-based discussions, we can persuade many hesitant individuals to reconsider.”

Villalobos emphasized a similar approach at Lehigh Valley Health Network.

“Our providers focus on building trust with vaccine-hesitant parents rather than criticizing them,” she said. “Many parents have never seen the diseases these vaccines prevent, so they don’t understand the risks. We work with them to address their concerns and provide accurate information.”

For those traveling to areas with active outbreaks, medical professionals stress the importance of vaccination.

“We offer travel clinics for families going abroad,” Villalobos said. “We ensure children receive all necessary vaccines before international travel, including an accelerated measles vaccination schedule for infants as young as six months. Given the rise in domestic cases, we also recommend ensuring full immunization before traveling within the U.S. to affected regions.”

Both experts urge the public to take measles seriously.

“This is not just a childhood illness – it can be deadly,” Jahre said. “There is no specific treatment for measles, so prevention through vaccination is crucial.”

Villalobos agreed.

“The more immunized children we have in the community, the less likely an outbreak will occur. Prevention is our best defense.”

As measles cases continue to emerge, health officials remain vigilant.

“We are closely monitoring the situation and will continue to update protocols as necessary,” Jahre said. “Our goal is to keep the community safe and informed.”