SACRAMENTO, Calif. (AP) — Giving California some of the strictest school vaccination requirements in the nation could help prevent outbreaks of disease like the measles flare-up at Disneyland, experts say.

Lawmakers introduced a measure eliminating the state's personal belief exemption for vaccines after the outbreak at the theme park in December infected over 100 people in the U.S. and Mexico. The bill likely would be successful in increasing immunization rates and stopping the spread of disease, pediatric doctors said Monday after the state Senate sent the legislation to the governor.

"Historically, we know that attaching requirements for school entry to vaccination has been one of the most successful ways to increase immunization rates," said Dr. Douglas Opel, a professor at the University of Washington who specializes in pediatric bioethics.

Under the bill, children without a medical exemption, which will still be granted to those with serious health issues, will have to be homeschooled or get fully vaccinated by kindergarten and seventh grade, the state's two vaccine checkpoints. A grandfather clause allows students currently claiming a personal belief exemption to maintain it until their next vaccine checkpoint.

The Senate reaffirmed the bill on a 24-14 vote Monday, putting California in line to join Mississippi and West Virginia as the states with the strictest requirements. It applies to public and private schools, as well as day care facilities.

The bill has sparked the most heated legislative debate of the year, with thousands of parents taking to social media and flooding the Capitol in recent weeks to protest. Similar legislation was dropped in Oregon earlier this year because opposition was so fierce.

California Gov. Jerry Brown, a Democrat, has not said if he would sign the bill, which he has 12 days to consider.

"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 has repeated in recent days.

Democratic Sens. Richard Pan and Ben Allen, the bill's sponsors, have said it is a crucial public health measure.

"The science remains unequivocal that vaccines are safe, that vaccines save lives," Pan said during Monday's floor debate.

Opponents have pushed back, saying the bill restricts parental rights with the false promise of stopping the spread of communicable disease.

"Patient zero can still come into our country and infect people," Sen. Joel Anderson said. "Patient zero isn't those unvaccinated kids. They're the victims of people, of our failure to ensure that we're providing a safe environment when foreigners come to our country, or when we've traveled abroad and brought back those diseases."

Dr. Eric Kodish, who specializes in pediatric ethics and oncology at the Cleveland Clinic, said there is significant evidence that legislating vaccines leads to real results.

"The combination of good law and good policy with face-to-face interactions with pediatricians will have an effect," he said.

The legislation aims to increase immunizations in regions that have seen a sharp drop. Though California's overall vaccination rates are stable, some suburban pockets have rates hovering near 50 percent. That poses problems for what immunologists call "herd immunity," or the percentage at which enough people are vaccinated to protect the whole community. Herd immunity for measles is between 92 and 94 percent, according to the Centers for Disease Control and Prevention.

Still, parents opposed to the bill are holding firm. They say it infringes on informed consent and violates equal access to education. Some have vowed to take legal action, though the issue has been upheld in court.

"I will sue to put my child in school," said Jude Tovatt of Roseville, parent of an 8-year-old. "I will not run from the state that is our home."

Other parents cheered the vote and turned their attention to swaying Brown.

"I know that he is very pro-science, and that's really what this bill comes down to: leadership in public health and supporting evidence-based science," said Hannah Henry, a mother of four from Napa who started Vaccinate California, a parental group in support of the bill. "That's where I'm expecting him to sign this bill."