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Health officials are warning travelers about a possible measles exposure at Philadelphia International Airport after a person with measles passed through the facility on Sept. 13 and into the early hours of Sept. 14. The Philadelphia Department of Public Health said the exposure involved Terminal B, Terminal F and connecting areas used for Terminals C, D and E, and the infected traveler did not leave the airport. The warning comes as the United States has recorded 3,294 confirmed measles cases in 2026 as of Sept. 10, already substantially above the 2,289 cases reported during all of 2025.
Where the Philadelphia Airport Exposure Happened
The Philadelphia exposure occurred from 7:25 p.m. Sunday, Sept. 13, until 12:05 a.m. Monday, Sept. 14, according to the city’s health department. Officials identified Terminal B and Terminal F along with areas used to connect to Terminals C, D and E as locations where travelers could have been exposed. The person with measles was passing through Philadelphia and remained inside the airport, and officials said this incident was separate from a recent measles exposure at Children’s Hospital of Philadelphia.
Why Measles Can Spread So Easily
Measles is considered one of the most contagious infectious diseases, and the virus can remain in an airspace for up to two hours after an infected person leaves an area. The CDC says as many as 90% of people who are close to an infected person and are not immune can become infected. Because people can spread measles from four days before through four days after the rash appears, a person can expose others before realizing they are sick.
Check Your MMR Vaccination Status
Philadelphia health officials are encouraging people who were at the airport during the exposure period to check whether they are protected against measles. The CDC says people can generally establish protection through the recommended number of measles-containing vaccine doses, laboratory evidence of immunity or previous measles infection, or being born before 1957. Anyone who is unsure about their vaccination history should speak with a healthcare provider, particularly after a potential exposure.
Symptoms Can Take Time to Appear
People exposed to measles do not necessarily become sick immediately, so health officials are asking potentially exposed travelers to monitor themselves for symptoms. Early symptoms can include fever, cough, runny nose and red or watery eyes, followed several days later by the characteristic measles rash. Anyone who believes they were exposed should contact a healthcare provider before going to a medical facility so staff can take precautions against exposing other patients.
2026 Has Seen a Major Increase in U.S. Measles Cases
The Philadelphia airport warning comes during a year when measles activity in the United States has risen sharply. The CDC reported 3,294 confirmed cases in 2026 as of Sept. 10, compared with 2,289 cases for the entire year of 2025, and 95% of the 2026 cases were associated with outbreaks. The agency also reported 38 new outbreaks in 2026 and cases across 47 jurisdictions, although the preliminary totals can change as health departments complete investigations and reporting.
Lower Vaccination Rates Can Leave Communities Vulnerable
The CDC says measles outbreaks can take hold when the virus reaches communities with groups of people who are not immune. National measles, mumps and rubella vaccination coverage among U.S. kindergartners declined from 95.2% during the 2019–2020 school year to 92.4% during the 2025–2026 school year, leaving an estimated 280,000 kindergartners at risk during that school year. Because protection varies by community, even areas with relatively high overall vaccination rates can contain pockets where measles can spread.
What to Do After a Possible Exposure
The CDC advises people who believe they have been exposed to measles to contact their healthcare provider immediately and explain the potential exposure. For people who are not immune, MMR vaccination or immune globulin may help reduce the risk of developing measles when given within the appropriate time after exposure, with the specific option depending on the person and timing. People who develop symptoms should call ahead rather than simply walking into a doctor’s office, hospital or other healthcare setting.
Travelers Should Pay Attention to Health Alerts
Airports can create opportunities for measles to spread because travelers from different communities and countries pass through crowded indoor spaces. The CDC notes that U.S. measles cases often originate with unvaccinated international travelers, and international travel can increase the chance of encountering measles where the disease is circulating. Travelers who do not know whether they are protected should discuss vaccination with a healthcare professional, especially before international travel or travel to areas experiencing outbreaks.
What the Philadelphia Warning Means for Travelers
The Philadelphia airport warning does not mean that everyone who passed through the terminal will become infected, but it does give potentially exposed travelers a reason to check their immunity and monitor for symptoms. Health officials specifically identified the locations and hours involved so people who were there can determine whether they may have been present during the exposure period. With measles cases already at their highest reported level in the United States in several years, health authorities continue to emphasize vaccination and prompt medical guidance following a known or suspected exposure.