Thousands of Oregon children would have to get vaccinated or stay out of school under a bill being prepared by Rep. Mitch Greenlick, D-Portland. The proposal comes amid a measles outbreak that has infected 52 children in Clark County, Washington, and has spread to Oregon, where four people have been infected. People in Bend were exposed to measles when a Clark County patient visited Bend in January before having symptoms.

Greenlick’s bill, which is still being finalized, would eliminate nonmedical exemptions for unvaccinated schoolchildren.

The goal, Greenlick said, is to protect those children who can’t get vaccinated for medical reasons.

“People have a right to make bad decisions about the health care of their children,” Greenlick said. “But that does not give them the right to send unprotected children into their school.”

At least 93 percent of children must be vaccinated to prevent outbreaks. One in five Oregon schools have measles vaccination rates below that threshold, according Oregon Health Authority data, with rates at some schools as low as 30 percent.

About 15,500 Oregon schoolchildren have nonmedical exemptions, according to state data. Under the lawmaker’s proposal, those kids would have to either get vaccinated or be home-schooled, Greenlick said.

Opposition could be stiff. A similar proposal in 2015 was abandoned following pressure from opponents. In Washington on Friday, hundreds protested a bill that would eliminate personal and philosophical exemptions to vaccines. And Greenlick has already received many calls from people accusing him of trying to restrict their freedoms, he said.

Greenlick blamed the opposition on scientific illiteracy and said it would not stop him from pursuing the bill. And he said he hoped his colleagues in the Legislature would be on board.

“I’ll just ask them to think carefully about it and to think about Vancouver,” he said. “We’ll try rationality.”

No new measles cases were announced over the weekend. The Clark County Public Health Department has identified 53 confirmed cases and two suspect cases since Jan. 1.