With measles breaking out in the Pacific Northwest, health experts in Utah say it’s more important than ever for parents to vaccinate their kids.

But two years after Utah’s latest measles outbreak, early childhood measles vaccination rates here are among the lowest in the country — and according to a study last year, the number of children seeking exemptions from school vaccine requirements for “personal” reasons is increasing.

“The best way of preventing the spread of measles is to have every single person in a community vaccinated, and to keep those who are infected at home, so they do not expose anyone else to this potentially deadly virus,” said Tamara Sheffield, medical director for community health and prevention at Intermountain Healthcare.

As of 2017, when there were three confirmed cases in Utah, the state’s measles vaccination rate among toddlers was 88.7 percent — 45th in the nation.

Almost 96 percent of school-aged kids were immunized, the state’s vaccination data show. But exemptions from vaccination requirements were on the rise, with more than 5 percent of kindergarteners seeking exemptions last school year.

If that trend keeps up, Utah could soon fall below a vaccination rate of 95 percent — the rate needed for “herd immunity” against measles, which is extremely contagious. Without that high rate of vaccinations, people who cannot get the shots become vulnerable.

“If we do not have at least 95 percent of the population vaccinated against measles there’s a good chance we’ll see outbreaks around the country,” said Rich Lakin, immunization program manager for the Utah Department of Health. “We’re only seeing the tip of the iceberg right now, I think.”

The vast majority of Utah’s vaccine exemptions were for “personal” reasons, rather than religious or medical reasons, according to the state’s report. Less than 1 percent of exemptions were for medical reasons.

“Across the country, we’re seeing an increase in exemptions,” Lakin said.

Utah was one of 12 states where number of “philosophical-belief” nonmedical exemptions has risen since 2009, according to a study in PLOS Medicine. Only 18 states allow vaccine exemptions for reasons that are not medical or religious, according to the study.

“My personal opinion is I’d like to see personal exemptions go away,” Lakin said. But that has proved politically difficult in other states, he said.

“There’s a lot of pushback” to revoking personal and philosophical exemptions, Lakin said. “The government is telling parents what to do, so it makes it very difficult to say, ‘No exemptions.’ There’s no talk in the Utah Department of Health or [among] any legislators that I know of … to bring that issue up.”

Although Utah is not reconsidering its exemptions, Lakin said, “I can tell you Washington is.”

At least 44 people in Washington and Oregon have fallen ill in recent weeks with the virus. More than a half-dozen more cases are suspected, and people who were exposed to the disease traveled to Hawaii and Bend, Oregon, raising the possibility of more diagnoses in the unvaccinated. The outbreak has led Washington’s governor to declare a public health emergency.

The measles virus typically causes a high fever, cough, runny nose and irritated eyes, followed by a flat red rash that may affect the face first and then spread to the rest of the body.

The measles, mumps, and rubella (MMR) vaccine is the only effective way to prevent it. The disease “is highly contagious, and people can spread it before they know they’re sick,” according to a statement from Intermountain Healthcare.

Measles can spread in the air for up to two hours after an infected person has left an area, according to the statement. Patients who believe they may have measles should call their doctors before arriving at appointments in order to arrange a place to meet that doesn’t expose others in a waiting room or examination room.

The measles vaccine was introduced in 1963 and measles was declared eradicated in the U.S. in 2000. In recent years, however, the viral illness has popped up again from New York to California and sickened hundreds.

The vaccine has been part of routine childhood shots for decades. While cases are extremely rare in this country, it is still a big problem in other parts of the world, and travelers infected abroad can bring the virus back and spread it, causing periodic outbreaks. Last year, there were 17 outbreaks and about 350 cases of measles in the United States.