Confirmed measles case tied to Canadian traveler who passed through Sea-Tac airport

SEATTLE — Public Health – Seattle & King County is warning travelers after being notified of a confirmed measles case involving a Canadian resident who traveled through Seattle-Tacoma International Airport on March 9, 2026.

The individual’s vaccination status is unknown. The infected person was at the airport before being diagnosed with measles and is no longer in King County, Health officials said Friday.

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Public Health urged anyone who is not immune to measles or does not know their vaccination status and was at the airport on March 9 to visit its measles webpage for specific information about potential areas of exposure within the airport.

Officials said that for people who were at Seattle-Tacoma International Airport on March 9 the most likely time they would become sick would be from March 16 through March 20.

“We are at a pivotal moment with more measles outbreaks happening throughout the U.S. and abroad. As a result, we may see more cases in King County. But getting vaccinated is a key step in preventing measles from spreading in our community,” said Dr. Sandra J. Valenciano,Health Officer for Public Health – Seattle & King County.

Measles can spread before an infected person knows they are sick and before any rash appears, according to Public Health.

There have been 28 cases of measles in Washington state residents so far in 2026, according to the Washington State Department of Health.