Island County Public Health is cautioning people who rode the Clinton-Mukilteo ferry on Dec. 30 about a possible measles exposure.

This week, health departments in both Snohomish and King counties reported three confirmed measles cases over the holiday season. One adult and two children in the same family were infectious from Dec. 27, 2025 to Jan. 1, 2026, when they were visiting from South Carolina. The children were not vaccinated.

Among the primary exposure sites was the Mukilteo-Clinton ferry from 1-3 p.m. on Dec. 30.

Measles causes flu-like symptoms followed by a spreading rash. The virus is highly contagious and can lead to serious complications, including pneumonia, brain swelling, deafness and even death, according to the Centers for Disease Control.

Island County Public Health reported that those who may have been exposed to take these action:

* Verify immunity: Check your records to ensure you have received the MMR (Measles, Mumps, and Rubella) vaccine.

* Stay home if symptomatic: If you develop a fever, cough, or other symptoms of measles, stay home and away from others to prevent spreading the virus to the community.

* Call ahead: If you need medical evaluation, you must call your health care provider before arriving at a clinic or ER. This allows the facility to take precautions so other patients are not exposed in the waiting room.