Health officials say they have 22 confirmed measles cases in Washington state since the start of the year.
Clark County Public Health is also investigating three suspected cases of the infection.
Officials say 19 of the people infected were not immunized and the three others were not verified to have had the vaccine.
Seventeen of the cases are children under 10 years old and four are youths from 11 to 18 years old. One person is between 19 and 29.