Travelers who passed through Philadelphia International Airport on the night of Sunday, Sept. 13, may have been exposed to measles, the Philadelphia Department of Public Health warned Saturday. The exposure window ran from 7:25 p.m. Sept. 13 to 12:05 a.m. Monday, Sept. 14, in Terminals B and F and in areas used to connect to Terminals C, D and E, according to 6abc Philadelphia.
The person with measles was traveling through the city and did not leave the airport, health officials said. The alert is unrelated to a separate exposure at Children's Hospital of Philadelphia (CHOP) on Sept. 11. Immune travelers face very little risk, but travelers who are not protected, including infants too young for the vaccine, should watch closely.
Timing is the reason for urgency. Measles symptoms can begin 7 to 21 days after exposure, according to the Pennsylvania Department of Health, so travelers who are not immune should watch for illness through Oct. 5. The standard windows for preventive treatment have likely closed for most travelers, which makes symptom awareness and a phone call before any clinic visit the most useful steps now.
Terminals, Times and the Monitoring Window
Measles spreads through the air when an infected person coughs, sneezes, or talks, and people who are not protected can catch it up to two hours after an infected person leaves a space. Anyone who spent time in Terminal B, Terminal F or the connecting areas during the listed hours should check whether they are protected.
CDC guidance allows the MMR vaccine to be given within 72 hours of exposure, and immune globulin within six days, to prevent or lessen illness. For an exposure on Sept. 13 that was announced Sept. 19, both windows have passed for most travelers. People who are not immune should still get vaccinated because a dose protects against future exposures, but it will not prevent illness from this one.
In its Sept. 17 notice about the CHOP exposure, the city advised people who are not immune and may have been exposed to wear a mask in indoor public spaces and around anyone unvaccinated until three weeks after exposure. The reason is that measles is contagious from four days before a rash appears, so someone can spread it before knowing they are sick.
Pennsylvania's Outbreak Raises the Stakes
The airport alert comes during Pennsylvania's largest measles outbreak in years. As of Sept. 18, the state Department of Health had confirmed 767 cases across 38 counties this year, with 150 hospitalizations and four confirmed measles-associated deaths. Only four cases, less than 1%, occurred in vaccinated people. On Sept. 16, the department began the formal process of requesting an Epi-Aid, an outbreak assistance team, from the CDC.
Residents are responding. Pennsylvania providers gave more than 46,000 MMR doses in August, compared with about 25,000 in a typical month, and more than 25,000 in the first two weeks of September, the state said.
Philadelphia is also managing the CHOP exposure, which involved the hospital's NICU West unit, its family lounge, the atrium and the main cafeteria on Sept. 11. The city said CHOP and state officials are working to give potentially exposed infants a preventive antibody product.
Nationally, the CDC had counted 3,294 confirmed measles cases this year as of Sept. 11, the most since 1991, with 95% in people who were unvaccinated or whose status was unknown, CIDRAP reported. Airports bring together people from many places, including infants and people with weakened immune systems who cannot rely on their own vaccination.
"Every Philadelphian who is fully vaccinated has little to fear from the situation at CHOP and the airport," Health Commissioner Dr. Palak Raval-Nelson said, adding that vaccinated residents are also helping protect the city's most vulnerable people.
Checking Immunity Without Adding to the Risk
City health officials generally consider people protected if they were born before 1957, have already had measles, or have received two doses of a measles-containing vaccine, usually MMR. The state health department says two doses provide about 97% lifetime protection, and people with two documented doses do not need another.
Records may be available through a primary care office, a childhood pediatrician, a state immunization registry, or old school or military files. Adults with only one documented dose, or no records at all, can ask a clinician or pharmacist about vaccination or a blood test to check immunity.
Three groups should contact a clinician promptly after a possible exposure rather than waiting for symptoms: infants younger than 12 months, pregnant people who are not immune, and people with weakened immune systems, according to the city's guidance.
Cost should not block protection. MMR vaccine is available through health care providers, pharmacies, county and municipal health departments, state health centers and federally qualified health centers, and eligible children can receive the vaccine through the Vaccines for Children program, the state said.
Symptoms and When to Call Ahead
Early measles symptoms include fever, runny nose, cough, and red, watery eyes, followed by a rash that starts on the head and spreads downward. The illness can lead to pneumonia, brain swelling, and death, and nearly 20% of people who get measles are hospitalized, according to the state.
Anyone who develops these symptoms should call a doctor's office, urgent care center, or emergency department before arriving and mention the possible airport exposure. That call lets staff take steps to limit exposure to others in a waiting room, which matters in a city already managing a NICU exposure. Philadelphia residents can call the health department at 215-685-6740, and other Pennsylvanians can reach the state at 877-PA-HEALTH (877-724-3258).
Trouble breathing, confusion, or seizures call for urgent evaluation.
Travelers who are fully vaccinated do not need to take action. For everyone else, the next two weeks are the period to watch. Updates on new exposure sites will be posted on the city's measles page, and national case counts are tracked on CDC's measles data page.
Key Questions Answered
Where and when was the exposure? At Philadelphia International Airport Terminals B and F and in areas connecting to Terminals C, D and E, from 7:25 p.m. Sunday, Sept. 13, to 12:05 a.m. Monday, Sept. 14.
Is this connected to the CHOP exposure? No. Philadelphia health officials said the airport case is unrelated to the probable exposure at Children's Hospital of Philadelphia on Sept. 11.
Who is considered protected? People born before 1957, people who have had measles, and people with two doses of a measles-containing vaccine are generally considered immune.
How long should exposed travelers watch for symptoms? Symptoms can begin 7 to 21 days after exposure, so travelers who are not immune should watch through Oct. 5.
What symptoms should people watch for? Fever, runny nose, cough, and red, watery eyes, followed by a rash that starts on the head and spreads downward.
Why call ahead before going to a clinic? Measles spreads easily through the air. Calling first lets staff take steps to protect other patients, including infants and people with weakened immune systems.
Can a vaccine still help? The MMR vaccine can prevent illness from an exposure only if given within 72 hours, a window that has passed. Vaccination still protects against future exposures.
