The Philadelphia Department of Public Health has warned patients, visitors and staff of a possible measles exposure at Children’s Hospital of Philadelphia, as Pennsylvania continues to confront a major outbreak of the highly contagious disease.
Health officials said the potential exposure occurred on Friday, September 11, 2026, at several locations inside CHOP’s main hospital at 3401 Civic Center Boulevard.
The Philadelphia health department issued the public alert on September 17 and said it is working with Children’s Hospital of Philadelphia and the Pennsylvania Department of Health to identify and protect people who may have been exposed.
Where the possible measles exposure occurred
According to the city health department, people may have been exposed at the following CHOP locations and times on September 11:
- CHOP NICU West: 9:30 a.m. to 4:15 p.m.
- NICU West Family Lounge: 9:30 a.m. to 4:15 p.m.
- CHOP Atrium: 9:30 a.m. to 4:15 p.m.
- CHOP Main Cafeteria: 12:05 p.m. to 2:45 p.m.
The inclusion of the hospital’s neonatal intensive care unit is particularly significant because very young infants can be vulnerable to serious complications from measles and may be too young to receive routine measles vaccination.
CHOP, state officials and Philadelphia health authorities are working to ensure potentially exposed infants receive a preventive antibody product intended to prevent infection or reduce the risk of severe disease, according to the city.
Officials urge people to check measles immunity
Anyone who was present at the listed locations during the exposure periods is being encouraged to check whether they are protected against measles.
The Philadelphia Department of Public Health said people are generally considered protected if they were born before 1957, previously had measles, or have received two doses of a measles-containing vaccine, typically the measles, mumps and rubella, or MMR, vaccine.
People who have received only one dose face a relatively low risk following the exposure but should speak with a healthcare provider about receiving a second dose, officials said.
Those who are not considered immune are advised to contact a healthcare provider about vaccination.
Infants younger than 12 months, pregnant people who are not immune and people with weakened immune systems should contact a healthcare professional as soon as possible because their management following a possible measles exposure may be different.
Exposed people should monitor for symptoms through October 2
Health officials are asking people who may have been exposed and are not immune to watch for symptoms through October 2, 2026.
Early measles symptoms can include:
- Fever
- Runny nose
- Cough
- Red, watery eyes
A rash generally develops afterward.
People who were potentially exposed, are not immune and develop symptoms should contact their healthcare provider immediately and tell the provider about the possible measles exposure before arriving for care, the city said.
The health department also advised potentially exposed people who are not immune to wear a mask in indoor public settings and around unvaccinated people for three weeks following exposure.
Measles can spread before a person realizes they are infected. People with the disease are considered contagious from four days before their rash begins until four days afterward, according to Philadelphia health officials.
The virus can spread through the air when an infected person coughs or sneezes, and an unprotected person can become infected even after the person with measles has left a room. The CDC says the virus can remain capable of infecting others in an airspace for up to two hours.
Pennsylvania reports more than 700 measles cases
The CHOP warning comes amid a much larger measles outbreak across Pennsylvania.
As of September 16, the Pennsylvania Department of Health had confirmed 731 measles cases across 38 counties in 2026.
The state had also recorded 141 hospitalizations and four measles-associated deaths, according to its latest statewide update. Only four confirmed cases involved appropriately vaccinated individuals, representing less than 1% of the state’s reported cases.
Philadelphia health officials said in their latest city update that there were no current confirmed cases in Philadelphia, although the statewide outbreak remains active and exposure alerts continue to be investigated.
The Pennsylvania Department of Health says two doses of the MMR vaccine are about 97% effective at preventing measles. The CDC also estimates effectiveness at approximately 93% after one dose and 97% after two doses.
Philadelphia Health Commissioner Dr. Palak Raval-Nelson urged residents who are not up to date on their vaccinations to get vaccinated amid outbreaks in Pennsylvania and elsewhere.
The city said it will publish additional information about confirmed exposures through its measles information service as necessary.
