California lawmakers proposed a bill Wednesday that would require parents to vaccinate all school children, unless the child is in danger.
Parents would no longer be able to cite personal beliefs or religions reasons to send unvaccinated children to private and public schools. The proposal would become the third state with similar restrictions after dozens of people have contracted measles that started at Disneyland.
Mississippi and West Virginia are the only other states to have strict vaccine rules, although the head of California's bill would consider a religious exemption.
"People are starting to realize, 'I'm vulnerable, my children are vulnerable,'" said Sen. Richard Pan, a Democratic pediatrician from Sacramento. "We should not wait for more children to sicken or die before we act."
The recent measles outbreak has sparked an emotionally charged topic of whether to vaccinate children. More than 100 people across the U.S. and Mexico have been sickened. No deaths have been reported.
Public health officials believe an immunization rate of 90 percent is critical to minimizing the potential risk of a disease outbreak. California's kindergartners met the threshold at the beginning of the school year.
Pan, who previously served in the Assembly, was the author of another vaccination bill that took effect last year. It requires parents who don't have their children vaccinated for non-religious reasons to get a note from the doctor's office before enrolling their children in school.
A spokesman for Gov. Jerry Brown, who signed that bill, did not say if the governor would oppose efforts to end exemptions.
"The Governor believes that vaccinations are profoundly important and a major public health benefit and any bill that reaches his desk will be closely considered," spokesman Evan Westrup wrote in an e-mail.
Parents cite a variety of beliefs for not vaccinating their children, including religious values, concerns that the shot causes illnesses like autism and a belief of allowing children to get sick to build a stronger immune system.
The Associated Press contributed to this report