PORTLAND, Ore. — The one-day immunization clinic at David Douglas High School in Portland, Ore., was hectic on Saturday, with a wait of 45 minutes to over an hour just to see a nurse. But Cameron Wagner said that after balking this long at getting her 4-year-old son vaccinated, out of concerns about potential side effects, a few more minutes would not matter.

“I’ve talked to more doctors and have weighed the options, and decided to come in and get a shot,” said Ms. Wagner, 46, a massage therapist.

Measles, which has broken out in the Pacific Northwest and elsewhere this year, was a major force in her changed thinking. She said she had been keeping Lux, her son, out of play spaces and other crowded public areas in recent weeks as alarming reports flooded the news, and she was tired of it.

As the outbreak has flared, vaccination rates have soared in a state where the percentage of kindergarten age children unvaccinated for nonmedical reasons — 7.5 percent, according to the Centers for Disease Control and Prevention — is the highest in the country. Parents of unvaccinated or undervaccinated children like Lux have come forward, raising health officials’ hopes that perhaps a corner has been turned. In Oregon and southwest Washington, where measles cases have clustered, about triple the number of children have been vaccinated this year, compared with the same period in 2018.