SEATTLE — Washington state has confirmed its first measles case of the year after a baby from King County tested positive, according to Public Health – Seattle & King County. The infant, who had recently traveled abroad, is believed to have contracted the illness during the trip.
Health officials confirmed the diagnosis on Thursday and warned that the child may have exposed others at multiple public locations throughout King County before the infection was identified. Because measles is airborne and spreads easily, exposure can occur even after an infected person has left a room — the virus can remain in the air for up to two hours.
Public Health officials are urging anyone who may have been at the same locations as the infant to confirm their immunization status and monitor for symptoms, particularly if they are not vaccinated. Measles symptoms typically develop between 7 to 21 days after exposure and can include a high fever, runny nose, cough, red or irritated eyes, and a distinct rash.
The infant was treated at several healthcare facilities, including the Seattle Children’s Emergency Department, which has since initiated patient notifications and infection control measures.
“A patient who visited our emergency department tested positive for measles,” a Seattle Children’s spokesperson stated. “Our staff followed protocol, isolating the patient and alerting Public Health. We are now contacting patients and families who may have been exposed, in line with privacy and safety procedures.”
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Health officials recommend those who suspect they’ve been exposed to measles call ahead before visiting any clinic or hospital to avoid exposing others. People are also encouraged to stay home, minimize contact with others, and wear a well-fitting mask if a medical visit is necessary.
Those who were potentially exposed and are not immune may begin experiencing symptoms between February 27 and March 18. Measles becomes contagious about four days before the rash appears and continues to spread for four days afterward.
Public Health – Seattle & King County is emphasizing the need for widespread vaccination. Measles is one of the most contagious diseases, with up to 90% of unvaccinated people in close contact with an infected person likely to get sick.
“We are seeing an uptick in measles cases both here and globally,” said Dr. Eric Chow, Chief of Communicable Disease at Public Health – Seattle & King County. “Checking your MMR vaccine status is critical—get vaccinated if you’re not protected.”
The MMR (measles, mumps, rubella) vaccine is extremely effective, with two doses offering approximately 97% protection. For the broader community to be protected through herd immunity, at least 95% vaccination coverage is needed. However, current estimates show only 87% of King County 2-year-olds and just 72% of 4–6-year-olds are fully vaccinated.
King County recorded three measles cases in 2024. Health officials fear this year could bring more cases if immunization rates don’t improve.
While measles is often survivable, it can lead to serious complications, particularly in children. According to the CDC, one in five unvaccinated individuals who get measles in the U.S. will require hospitalization. Among children, pneumonia affects one in 20, and about 1 in 1,000 may develop encephalitis, a potentially deadly brain inflammation. In rare cases, measles can be fatal—especially among young children.
Pregnant individuals without immunity also face higher risks, including premature birth or low birthweight babies.
Regarding boosters, most people who received two doses of the MMR vaccine in childhood are well-protected for life. However, healthcare workers and people in high-risk environments—such as those with chronic health issues or who live with an infected person—may be advised to get tested for immunity or consider a booster.
For details on measles symptoms, exposure guidance, and where to get vaccinated, residents can visit the King County Public Health website.
