UPDATE March 17, 2025: Public Health – Seattle & King County and Snohomish County Health departments are investigating a positive case of measles, identified on March 17, in an adult resident of Snohomish County. Health officials say that the new case is linked to a case of measles identified in an infant in late February in King County.
The person was likely exposed at a location where the baby visited while contagious. However, the departments believe there were no additional public exposures when the Snohomish County adult was contagious and have determined no increased risk to the general public associated with the new case.
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Public Health – Seattle & King County has sent out a warning in late February about the first confirmed case of measles of the year—found in an infant on February 28— in a King County. They urged those who might have been exposed to the child to check their vaccine status.
The infant may have been exposed to measles during recent travel abroad.
Measles rash. (Image: iStock.com)
Potential exposure dates, times and locations
Measles virus can remain in the air for up to two hours after someone contagious with measles leaves the area. If you or your child is not immune to measles and was exposed, the most likely time you would become sick would be between February 27 – March 18, 2025. People with weakened immune systems may take longer to experience symptoms. Anyone who was at the following locations during the times listed below could have been exposed:
- Feb. 20: 6 to 9 p.m. at the Bellevue Square Apple Store located at 213 Bellevue Square, Bellevue, WA 98004
- Feb. 21-22: 10:30 p.m. to 2:15 a.m. at Seattle Children’s Hospital Emergency Department, located at 4800 Sand Point Way NE, Seattle, WA 98105
- Feb. 24: 1:00 p.m. to 4:15 p.m. at Allegro Pediatrics, located at Bothell 11724 NE 195th St, Ste 100, Bothell, WA 98011
- Feb. 25: 1 to 4:00 p.m. at Northwest Asthma & Allergy Center, located at 8301 161st Ave NE, Ste 308, Redmond, WA 98052
- Feb. 25: 2:30 to 5:30 p.m. at Seattle Children’s Hospital Emergency Department, located at 4800 Sand Point Way NE, Seattle, WA 98105
What to do if you were in a location of potential measles exposure
Most people in our area have immunity to measles through vaccination, so the risk to the general public is low. However the disease can be dangerous to for high risk groups, including unvaccinated kids under age five and pregnant people. Severe disease causes fever, rash, cough, runny nose, and red, watery eyes. The disease can cause ear infections, diarrhea, pneumonia, and rarely, encephalitis (brain inflammation) or death.
It mainly spreads through the air after a person with measles coughs or sneezes. However, anyone who was in the locations of potential exposure to measles around the times listed should:
- Find out if you have been vaccinated for measles or have had measles previously. Make sure you are up to date with the recommended number of measles (MMR) vaccinations.
- Call a healthcare provider promptly if you develop an illness with fever or with an unexplained rash. To avoid possibly spreading measles to others, do not go to a clinic or hospital without calling first to tell them you want to be checked for measles after an exposure. It is also important to limit contact with others, especially those without known immunity, and to wear a well-fitting mask if you do need to go to a healthcare facility.
Vaccination is key
“Measles is easily spread from person to person. If one person has it, up to 9 out of 10 people nearby will become infected if they are not protected,” said Dr. Eric Chow, the department Communicable Disease Chief in an announcement. “We are seeing increases in measles cases within and outside the U.S. Talk to your doctor about checking your vaccination status and get vaccinated now if you aren’t already protected.” Two doses of the measles, mumps and rubella (MMR) vaccine provides about 97% protection against getting infected by measles and that protection lasts a lifetime PHSKC officials say.
In 2024, there were three cases of measles in King County. Herd immunity, which helps prevent rapid spread of diseases among a large population, requires about 95% of people to be vaccinated against measles because it is so infectious. We are likely to see more frequent and larger outbreaks when vaccination rates are lower than that.
- An estimated 87% of 2-year-olds in King County are up to date on the MMR vaccine (having received one dose of the MMR vaccine).
- An estimated 72% of 4–6-year-olds in King County have received 2 doses of the MMR vaccine.
Groups at highest risk include: infants and children under 5 years, adults over 20 years, pregnant people, and people with weakened immune systems from medications or underlying disease.
About the disease
Measles symptoms begin 7 to 21 days after exposure. Measles is contagious from about 4 days before the rash appears through 4 days after the rash appears. People can spread measles before they have the characteristic measles rash. For more information about measles and measles vaccination, including where to get measles vaccinations: www.kingcounty.
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