On May 13, 2025, Seattle & King County was notified of a confirmed measles case in a Canadian resident. The person spent time in King and Snohomish counties between April 30 and May 3, 2025, while infectious. The individual’s vaccine status is unknown. 

In addition to traveling through Seattle-Tacoma International Airport, the person visited multiple public locations in Renton, Bellevue, Seattle, Everett and Woodinville while contagious with measles, but before being diagnosed with measles. If you are not immune to measles, or don’t know your vaccination status, please see the list below for locations of potential exposure.

This case is not connected to any previous local measles cases. Public Health has responded to two other measles cases this year among people who traveled through King County but are not Washington state residents. There have been five cases of measles in Washington state residents this year.

Measles is a highly contagious and potentially severe disease that causes fever, rash, cough, runny nose, and red, watery eyes. If one person has it, up to 9 out of 10 people nearby will become infected if they are not protected. It mainly spreads through the air after a person with measles coughs or sneezes.

Measles is preventable with the safe and highly effective measles, mumps and rubella (MMR) vaccine. Two doses of the MMR vaccine are about 97% effective at preventing measles and that protection is long lasting.