St. Luke’s University Hospital said late Monday that it’s treating its first cases of the measles “in recent memory.”

According to a health network spokesperson, the hospital was treating two children from Lehigh County. The two are siblings, and both were unvaccinated, the spokesperson said.

The network did not specify where in Lehigh County the siblings were from. Dr. Jennifer Janco, chair of pediatrics at St. Luke’s, said one was hospitalized but released, and both are recovering at home.

Janco said the network already completed contact tracing for its networks and that there were no potential exposures at any St. Luke’s facilities. All other contract tracing is being conducted by the Pennsylvania Department of Health. Janco said that the children had traveled internationally and there were multiple potential places where they could have come in contact with measles.

St. Luke’s last month warned of an eastern Pennsylvania outbreak of the highly infectious disease and encouraged parents to take extra steps to protect their children.

Seventy-five infections were linked to an outbreak that began in Lebanon and Lancaster counties in late April. Two cases were reported in Berks County, according to the Pennsylvania Department of Health. Across the state, so far there have been 176 confirmed cases of measles in 2026, with 35 reported in the last seven days.

Because of the outbreak, the Health Department is recommending infants ages 6-11 months receive an early dose of the measles, mumps and rubella vaccine. Children who have already received one MMR dose at 1 year of age, which is the typical age the first doses are given, may be eligible to receive their second dose earlier than their fourth year, which is the usual time the second dose is given.

“Measles is one of the most contagious infectious diseases, but vaccination is the safest and most effective way to protect your child and those around them,” Janco said.

The St. Luke’s measles cases are the first known ones reported in the Lehigh Valley since 2019. An Allentown resident at Lehigh Valley Hospital-Cedar Crest with measles marked the city’s first case in more than 20 years, officials said at the time. It caused five people who were potentially exposed to be ordered to quarantine, including one who received a rare court order to do so.

There were two potential measles exposures in 2011, according to previous reporting by The Morning Call.

Since the introduction and adoption of the measles vaccine in the 1960s, measles cases in the Lehigh Valley have been rare. The last known death from measles in the Lehigh Valley was a Bethlehem Township girl who died in 1991 after she contracted the disease in Philadelphia amid a major national outbreak. Later that year, six children in the Lehigh Valley got measles, as part of an outbreak that affected at least 14 children in Lehigh, Northampton, Lancaster and Lebanon counties.

Before the introduction of the vaccine, measles was a serious and pervasive threat that often seriously disrupted school and everyday life.

In 1912, The Morning Call reported that one child being sent to school sick with measles resulted in 12 Lehigh Valley schools temporarily closing and 14,000 students missing school to prevent exposure amid a national measles outbreak. In winter 1916, another national outbreak led to hundreds of people in Allentown getting infected with the disease and the entire city being placed under quarantine, with all schools shut down for several weeks. Yet another national epidemic of measles in 1923 led to at least 500 people in Allentown getting sick in January, February and March, and on one day in May 1923, there were 64 school children in Alburtis, nearly a third of the students in the town, who were out sick with measles.