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Measles cases across the U.S. have climbed to more than 3,400 this year as health officials warn that travelers may have been exposed to the highly contagious virus at Philadelphia International Airport. The Philadelphia Department of Public Health said a traveler with measles passed through the airport between 7:25 p.m. on September 13 and 12:05 a.m. on September 14. The traveler was in terminals B and F, as well as areas connecting to terminals C, D and E, but did not leave the airport.
The warning comes during a resurgence of measles cases across the country, with Pennsylvania currently the worst impacted state in the U.S. The Centers for Disease Control and Prevention ( CDC ) has said 3,471 confirmed cases had been reported nationwide as of September 17, already exceeding the 2,289 cases recorded during the entirety of 2025. Philadelphia Airport Warning Officials have urged people who were in those areas during the exposure window to check whether they are protected against measles and monitor themselves for symptoms.
Those who are not immune, are unsure of their vaccination status, are infants, pregnant and not immune, or immunocompromised have been advised to contact a health care provider. People who may have been exposed and develop symptoms through October 5 should contact their doctor immediately and tell them about the possible exposure before arriving at a health care facility, the department said. The airport warning followed a separate possible measles exposure at Children's Hospital of Philadelphia on September 11.
City officials said the two cases were not connected. "This week’s measles exposures are a reminder of how important it is for all of us to be up to date on our vaccinations," Philadelphia Health Commissioner Dr. Palak Raval-Nelson said.
"Every Philadelphian who is fully vaccinated has little to fear from the situation at CHOP and the airport. Even more importantly, every one of those people is doing their part to help protect our most vulnerable from measles. With outbreaks continuing in Pennsylvania and other places, this is even more important." Measles Outbreak The CDC has recorded 39 new outbreaks in 2026, with 95 percent of confirmed cases—3,296 infections—associated with outbreaks.
The agency's figures are updated weekly and include confirmed cases reported by state and local health departments. The CDC says the state worst impacted by the measles outbreak this year is Pennsylvania, which has recorded 745 cases in 2026 alone, up from just 16 cases in 2025. South Carolina follows with 670 cases this year compared to 333 the year prior, and Utah has had 527 recorded infections compared with 189 in 2025.
Other states that have recorded more than 100 cases this year are Texas, Virginia, Wisconsin, Florida, Ohio and Arizona. Some states are faring better this year than they were last year. Texas recorded 803 infections in 2025, with 192 reported this year.
In Arizona, there have been 110 so far in 2026, but in 2025 recorded 222 measles cases. Only five states have not recorded any cases in 2026 so far: Arkansas, Hawaii, Mississippi, New Hampshire and Nevada. What Are Measles Symptoms?
Measles is an acute viral illness that is highly contagious. Symptoms generally begin seven to 14 days after infection and initially include a high fever, cough, runny nose and red, watery eyes. Small white spots can develop inside the mouth before a rash appears on the body, usually around three to five days after the first symptoms and spreading from the head downward. ...
Measles can also lead to serious complications, including pneumonia and brain inflammation, with babies, young children, pregnant women and people with weakened immune systems having a higher risk of developing a serious infection. How Does Measles Spread? Measles spreads through the air when an infected person coughs or sneezes, and the virus can remain in an airspace for up to two hours.
People with measles can spread the virus from about four days before the rash appears until four days afterward. Among people who are not immune, the CDC says up to 90 percent of those close to someone with measles can become infected. Can You Get Measles If You Are Vaccinated?
People can still get measles after being vaccinated , although breakthrough infections are rare. The CDC says one dose of the measles, mumps and rubella (MMR) vaccine is 93 percent effective at preventing measles, and two doses are 97 percent effective. Vaccination can also reduce the severity of an infection if it does occur.
The CDC says people who develop measles despite having preexisting immunity tend to have milder illness, are less likely to develop complications and are less likely to transmit the virus to others. The latest outbreak comes as childhood vaccination coverage of measles has continued to decline. MMR coverage among U.S. kindergartners fell to 92.4 percent in the 2025 to 2026 school year, while about 280,000 kindergartners attended school without documentation that they had completed the MMR vaccine series.
Exemptions from one or more vaccines increased to 4.2 percent, from 3.6 percent a year earlier. The CDC reports that 44 percent of all infections so far this year have been among those aged 5 to 19 years old, and 18 percent have occurred in children under 5. Confidence in the vaccine has also fallen.
A Reuters/Ipsos poll published September 15 found that 76 percent of Americans believed vaccines against measles, mumps and rubella were safe for children, a near 10 point drop from 84 percent in May 2020. However, the survey also found that a bipartisan majority continue to support vaccinating children against measles. Contact Newsweek editors on this story: Ben Kelly and James Debens
Source: Newsweek
