It may be that a measles outbreak currently plaguing Clark County, Washington, won’t spread to Oregon. Don’t bet on it. The outbreak apparently traces its roots to three Portland locations: the airport, an Ikea store nearby and a Portland Trail Blazers game.

If more Oregonians were vaccinated against measles, that wouldn’t be a problem. But in some counties, including Multnomah and Deschutes, vaccination rates are often so low that children and adults who cannot for health reasons receive the medications are in danger of catching measles and the other diseases we can now prevent with routine vaccination.

As of Thursday, at least 25 people in Clark County have come down with measles since the first week in January, 18 of whom are children 10 years old or younger. One person was admitted to the hospital and later released. No one has died, but the outbreak is far from over, health authorities say.

The vaccine against measles is 97 percent effective, and disproved theories to the contrary, it does not cause autism. There are children and adults who should avoid the vaccine, but it’s safe for most of us and a doctor can tell you who shouldn’t receive it.

Knowing all that, the Oregon Legislature should act to tighten the state’s immunization requirements during this session. Not since state Sen. Elizabeth Steiner Hayward proposed ending philosophical exemptions from immunization in 2015 has there been a serious push at improving the situation. The state’s opt-out law, adopted in 2015, did cut the number of unvaccinated children, to be sure. Today, unfortunately, those gains have disappeared.

Steiner Hayward, a pediatrician, is all too aware of the dangers that come when too many kids go unvaccinated. She’s had the courage to go up against immunization opponents before, and if Oregonians are lucky, she’ll have that same courage this year. And this time, lawmakers from both parties should sign on to her effort.