Mumps Outbreak Worsens in Washington State, With Nearly 300 Reported Cases

Hundreds of students have been told to stay home to avoid getting sick.

There are at least 166 likely cases in King County, where Seattle is located, and 94 cases in Spokane, where at least 300 students were told to stay home due to concerns they were not up to date on their vaccinations, the health departments in those counties said Thursday.

“Because some people do not get lasting protection from the vaccine and mumps spreads easily from person to person, outbreaks can still occur in vaccinated populations," Dr. Jeff Duchin, health officer for public health, Seattle and King County, said in a statement earlier this month. "But, if unvaccinated, many, many, more people would become ill.”

A community should be between 75 to 86 percent vaccinated in order to prevent an outbreak of mumps, according to UNICEF.