Second measles case identified in Washington state

Public Health – Seattle & King County and Snohomish County Health Department are investigating a positive case of measles, identified on March 17, 2025, in an adult resident of Snohomish County. This case is linked to the first measles case identified in late February in King County. This new case was likely exposed at a location where the previous case had visited while contagious.

King and Snohomish County health departments assessed any potential public exposures while the individual was contagious and determined that there is no risk of measles to the general public from this new case.

Fortunately, the measles vaccine is very effective. 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.

"Measles spreads easily in communities with low immunity, which is why maintaining high vaccination rates is so critical," said Dr. James Lewis, Health Officer for the Snohomish County Health Department. "We have confirmed a second measles case; without the rapid response from public health departments to conduct contact tracing to identify susceptible individuals, we could have seen significantly more cases. While there are some prevention steps like immune globulin and the MMR vaccine that can prevent infection when given promptly after exposure, supplements like vitamin A, cod liver oil, or other alternative remedies will not stop measles from spreading. Measles exposure in the community puts vulnerable people—especially infants, pregnant individuals, and those with weakened immune systems—at serious risk. Measles is highly contagious, but also highly preventable with vaccination, and ensuring people are fully immunized remains our best defense."

“Measles is more than just a rash and can be a very serious infection that affects different parts of the body. It’s hard to watch a loved one experience an illness due to measles,” said Dr. Eric Chow, Communicable Disease Chief for Public Health – Seattle & King County. “Unfortunately, measles is very contagious and people who are not fully vaccinated are at risk. Talk to your doctor about checking your vaccination status. By getting up to date with the MMR vaccine, we protect ourselves and our loved ones from infection.”