Measles case identified in a King County infant

Summary

Public Health – Seattle & King County is informing the community of a confirmed measles case in a King County infant who may have exposed others to the measles virus.

Story

Public Health – Seattle & King County was notified of a confirmed measles case in a King County infant. The infant was at locations in Bellevue and Northeast Seattle and used public transit while infectious. Spread of measles can occur before people know they have the disease, before a rash appears. Please visit kingcounty.gov/measles for specific location information.

The individual was likely exposed to measles during recent international travel. The infant had not yet been vaccinated. This case is not connected to any of the previous local measles cases. Prior to this case, there have been 33 cases of measles in Washington state in 2026.

“Outbreaks have been happening in the U.S. and internationally. As you prepare for spring and summer travel, it’s important to know your measles immunity status before you travel. Babies ages 6-11 months should get an early dose if traveling internationally or to places in the U.S. with current measles outbreaks,” said Dr. Sandra J. Valenciano, Health Officer and Acting Director for Public Health – Seattle & King County.

Fortunately, the measles vaccine is very effective. Two doses of measles, mumps and rubella (MMR) vaccine provides about 97% protection against getting infected by measles and that protection lasts a lifetime. 

What to do if you were in a location of potential measles exposure 

Most people in our area have immunity to measles through vaccination, so the risk to the general public is low. However, anyone who was in the locations of potential exposure to measles around the times listed should: 

• Find out if you have been vaccinated for measles or have had measles previously. Make sure you are up-to-date with the recommended number of measles (MMR) vaccinations. 

• Call a healthcare provider promptly if you develop an illness with fever or with an unexplained rash. To avoid possibly spreading measles to others, do not go to a clinic or hospital without calling first to tell them you want to be checked for measles after an exposure. It is also important to limit contact with others, especially those without known immunity. 

If you were at the locations at the times listed on the website and are not immune to measles, the most likely time you would become sick would be between April 10, 2026 – April 29, 2026. People who are immuno-compromised may take longer to experience symptoms. 

About measles 

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 symptoms begin 7 to 21 days after exposure. Measles is contagious from about 4 days before the rash appears through 4 days after the rash appears. People can spread measles before they have the characteristic measles rash. 

Measles can lead to ear infections, diarrhea, pneumonia, and rarely, encephalitis (brain inflammation) or death. 

Complications from measles can happen even in healthy people, but those at highest risk include infants and children under 5 years, adults over 20 years, pregnant people, and people with weakened immune systems from medications or underlying disease. 

If you are in one of these high-risk groups and were exposed to measles at one of these locations, be sure to contact your health care provider to discuss any steps you need to take to protect yourself or loved ones against complications from measles. 

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. 

For more information about measles and measles vaccination, including where to get measles vaccinations: www.kingcounty.gov/measles