King County confirms measles case; public warned of possible exposure

A King County infant has tested positive for measles in the year’s first confirmed case in a Washington resident.

The child might have been exposed to the highly contagious disease while traveling abroad, King County’s public health department said in a Thursday notice. It’s possible other people who were near the infant in certain public places around the county, including Seattle Children’s hospital, could have also been exposed between Feb. 20-25, the statement said.

“Measles is easily spread from person-to-person,” said Dr. Eric Chow, communicable disease chief for Public Health — Seattle & King County, in the statement. “If one person has it, up to 9 out of 10 people nearby will become infected if they are not protected.”

Public health officials declined to provide the child’s age but said they are under 12 months old and are currently hospitalized.

The U.S. Centers for Disease Control and Prevention recommends children get two doses of the routine childhood MMR (measles, mumps and rubella) vaccine, one between 12 and 15 months old and the second when they’re 4 to 6 years old. However, the agency also advises 6- to 11-month-old infants who are traveling abroad to get one MMR dose before leaving the country, public health spokesperson Sharon Bogan said in an email. The King County child now in the hospital with measles, and who had been out of the country, had not received that single MMR dose, local health authorities said.

Although measles was declared eliminated from the U.S. in 2000, it’s still common in other parts of the world and can be brought into the country by unvaccinated travelers, according to the CDC. In recent months, outbreaks in Texas and New Mexico have sickened nearly 100 people, most of whom had not received shots against measles, The New York Times reported. A child in Texas has died.

This year, an Alaska resident also tested positive for measles while traveling through Seattle-Tacoma International Airport. In 2024, three measles cases were confirmed in King County.

The new cases come as public health experts express growing concern about the decline in childhood vaccination rates in the last several years. The worry has heightened for many as Robert F. Kennedy Jr. takes the helm at the Department of Health and Human Services after decades spent making false claims to undercut the established science showing vaccines as safe and effective.

In King County, about 87% of 2-year-olds are up-to-date on the MMR vaccine, meaning they’ve received one dose, and about 72% of 4- to 6-year-olds have received both doses.

Herd immunity requires about 95% of people to be vaccinated against measles because it’s so infectious. We’re likely to see more frequent and larger outbreaks when vaccination rates are lower than that, the county said.

“We are seeing increases in measles cases within and outside the U.S.,” Chow said in the statement. “Talk to your doctor about checking your vaccination status and get vaccinated now if you aren’t already protected.”

The MMR vaccine is very effective against the highly contagious disease. Two doses provide about 97% protection against getting infected throughout a person’s entire life, according to the CDC.

Measles can cause fever, rash, cough, runny nose and red, watery eyes and can sometimes lead to ear infections, diarrhea, pneumonia and, rarely, encephalitis (brain inflammation) or death. Symptoms typically begin seven to 21 days after exposure and can be contagious from about four days before a rash appears through about four days afterward, according to public health officials.

The disease mainly spreads through the air after someone with measles coughs or sneezes. Those at highest risk include children under 5, adults over 20 and those who are pregnant or have underlying health conditions. But complications can also happen in healthy people, public health officials said.

Possible public exposure locations

There are four spots throughout King County where people might have been exposed to the infant who tested positive for measles this week.

Because most people in the county have been vaccinated against measles, the risk to the general public is low, public health officials said. But because the virus can stay in the air for up to two hours after someone with measles leaves the area, anyone who might have been in these locations during these times should figure out if they’ve received an MMR shot and call their health care provider, public health officials said.

The locations and potential windows of exposure include:

• Thursday, Feb. 20, between 6- 9 p.m.: Apple Store at Bellevue Square (213 Bellevue Square, Bellevue)

• Friday, Feb. 21, through Saturday, Feb. 22, between 10:30 p.m.-2:15 a.m.: Seattle Children’s emergency department (4800 Sand Point Way NE, Seattle)

• Monday, Feb. 24, between 1-4:15 p.m.: Allegro Pediatrics location in Bothell (11724 NE 195th St., Suite 100, Bothell)

• Tuesday, Feb. 25, between 1-4 p.m.: Northwest Asthma & Allergy Center (8301 161st Ave. NE, Suite 308, Redmond)

• Tuesday, Feb. 25, between 2:30-5:30 p.m.: Seattle Children’s emergency department (4800 Sand Point Way NE, Seattle)

If you think you’ve been exposed to measles, do not show up at a clinic or hospital without calling first, Public Health — Seattle & King County said. To avoid possibly spreading measles, limit contact with others and wear a well-fitting mask if you need to go to a health care facility, the department said.

If you were at the locations at the times listed above and are not immune to measles, the most likely time you would become sick would be between Feb. 27 and March 18, according to the department.

More information about vaccines and other resources is available at www.kingcounty.gov/measles.