The Oregon Senate has passed a bill that would require parents to consult a physician about vaccines or watch an educational video before refusing them for their children.
In a 16-13 vote on Thursday, the Senate approved the bill, which now goes to the House.
Oregon has the nation's highest rate of parents refusing vaccinations for their kindergartners.
Doctors and public health officials say the rate of unvaccinated children in Oregon is alarming and should be brought down.
Opponents say the measure infringes on religious freedoms.
Parents now sign a form to exempt their children from vaccinations for religious or philosophical reasons.
The bill would require parents to prove they consulted a physician or viewed an educational video before opting out of vaccines for their children.