Two California state senators proposed legislation Wednesday that would ban parents in the state from claiming “personal belief exemptions,” which excuse children from getting the standard vaccines required to attend public schools.

The move comes as the state copes with a measles outbreak, which has been linked to the increasing incidence of parents in the state choosing not to immunize their children. The bill, proposed by state senators Dr. Richard Pan and Ben Allen, will focus on the vaccinations required to attend public school. In some California schools, between 60 percent and 70 percent of parents have filed so-called "personal belief exemptions" for their children. As a result, some of the state's wealthiest neighborhoods now have vaccination rates on par with Chad or South Sudan, according to the Atlantic Monthly.

“As a pediatrician I have personally witnessed children suffering lifelong injury or death from vaccine-preventable infection," Pan said, according to CNN.

Allen added, in a written statement, cited by Reuters: "The high number of unvaccinated students is jeopardizing public health not only in schools but in the broader community. We need to take steps to keep our schools safe and our students healthy.”

If the bill is passed, parents would only be able to have their children opt out of vaccinations for medical reasons. Around 2.5 percent of California parents currently hold “personal belief exemptions” for their children, according to KCBS News.

"Immunization of a person shall be required for admission to a school or institution ... unless the child has a physical condition or medical circumstances that contraindicate vaccination as prescribed in Section 120370," the measure reads, according to the Huffington Post.

California Gov. Jerry Brown -- who fought for more parental choice just two years ago -- quickly signaled that he was open to reform.

"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," Evan Westrup, Brown's spokesman, told the San Jose Mercury News.

Measles was declared eradicated in the U.S. in 2000, but a case believed to have originated in a Disneyland theme park in California has led to a larger outbreak, and 92 of the approximately 100 cases diagnosed so far in the country are in the state. The measure, if passed, would make California the thirty-third U.S. state to ban parents from refusing to vaccinate their children based on personal beliefs.