SEATTLE (AP) _ A local health official says a woman killed by measles in Washington state had been vaccinated against the disease as a child but succumbed because she had a compromised immune system.

The woman’s death in the spring was the first from measles in the U.S. in 12 years.

Dr. Jeanette Stehr-Green, the Clallam County health officer, told KOMO-TV the woman had been vaccinated as a child, but because she had other health problems and was taking medications that interfered with her response to an infection “she was not protected.”

Washington Health Department spokesman Donn Moyer says the Washington woman lacked some of the measles’ common symptoms, such as a rash, so the infection wasn’t discovered until an autopsy.