Measles in King County continues to spread, with two new cases confirmed in a local household—a child and an adult—bringing the state’s total to 10 for 2025. According to Public Health – Seattle & King County, the individuals visited multiple public locations while infectious, potentially exposing others throughout the region.
Exposure Risk
Prior to their diagnoses, both individuals visited multiple King County locations — including Bellevue, Issaquah, Mercer Island, Newcastle, and Seattle — during their infectious periods. Because measles is airborne and remains viable in enclosed spaces up to two hours after an infected person leaves, anyone present at those sites during the specified times could have been exposed. Please see the chart below for exact exposure times and locations.
(Image courtesy Public Health – Seattle & King County)
Vaccination & Transmission Background
- The child had received one dose of the MMR vaccine.
- The adult’s vaccination status remains unknown.
- The household’s likely source was an international visitor who displayed symptoms and has since left the area.
These cases are not linked to earlier measles cases in the region.
Expert Insights
A recent article on Seattle’s Child, featuring pediatric expert Dr. Mary Fairchok, sheds further light on measles:
- Early symptoms—fever, cough, runny nose, red eyes — often appear before the signature rash, making early identification tricky.
- Vaccination remains key: one dose of MMR produces ~93% protection, while two doses offer ~97%, ensuring long-term immunity.
- Dr. Fairchok emphasizes that measles can be more serious than commonly thought, with potential for complications like pneumonia, encephalitis, and prolonged immune suppression—even in previously healthy children.
Public Health Recommendations
Dr. Meagan Kay, Medical Epidemiologist at Public Health – Seattle & King County, advised:
“With more measles cases globally and in the U.S., if you are planning to travel, make sure you’re up to date on all your vaccinations… get vaccinated at least two weeks before your trip.”
Two MMR doses grant about 97% protection for life — a cornerstone in preventing outbreaks.
What You Should Do
- Check your MMR records—especially if you’ve had only one dose or none.
- Monitor for measles symptoms: fever, cough, runny nose, red eyes, and rash.
- If you visited any of the listed locations during the alert times, contact your healthcare provider — particularly if you’re unvaccinated, pregnant, or immunocompromised.
- Vaccinate promptly: MMR can still reduce disease severity if given soon after exposure.
Bottom Line
Although rare, thanks to high vaccination rates, measles remains a serious public health threat. These recent cases in King County — and expert commentary via Seattle’s Child—underscore the importance of staying fully vaccinated, recognizing early symptoms, and responding quickly to potential exposure. Ongoing vigilance is key to containing measles outbreaks.
