Gov. Jerry Brown on Tuesday signed one of the strictest schoolchild vaccination laws in the country, eliminating personal and religious belief exemptions for vaccines.

The governor’s signature came one day after the state Senate moved the bill to his desk, following months of protests and fierce debate at the Capitol.

“The science is clear that vaccines dramatically protect children against a number of infectious and dangerous diseases,” Brown said in a signing statement. “While it’s true that no medical intervention is without risk, the evidence shows that immunization powerfully benefits and protects the community.”

The bill will make California the third state in the nation to require vaccines without religious and personal belief exemptions.

Opponents of the measure said it unfairly restricts parent choice. They immediately vowed to challenge the law in court and potentially through a referendum at the ballot box, arguing it will deprive unvaccinated children of their constitutional right to an education.

“We need to wait until someone actually gets thrown out of school until we can challenge it,” which would not occur until after the bill takes effect in 2016, said Christina Hildebrand, founder of the group A Voice For Choice. “But we will likely have a referendum on it.”

Proponents of the legislation, spurred by a measles outbreak at Disneyland, said unvaccinated children put kids who are too young or sick to be vaccinated at risk.

“Parents do not need to worry, do not want to worry, about taking their children to the school, or to stores, to theme parks,” said bill author Richard Pan, a Democratic state senator from Sacramento.

Of the possibility of a legal challenge, he said, “The courts have been very clear that you don’t have a right to spread a communicable disease, that there’s a public interest in keeping our communities safe from disease.”

The bill allows any schoolchild with an exemption on file to remain unvaccinated until he or she starts kindergarten or, if already in elementary school, seventh grade.

Thousands of California parents protested the measure, Senate Bill 277, in recent months, including at a vigil outside the Capitol this week.

When she heard at the vigil that Brown had signed the bill, Kimberly McCauley of Sacramento sat down on the steps and cried.

McCauley carried pictures of her 2-year-old daughter Ella, whom she said she stopped vaccinating after Ella had adverse reactions to three immunizations, and a letter from her pediatrician denying Ella a medical exemption.

“My daughter is the sweetest little girl, and every day she asks when she gets to go to school,” McCauley said, choking back more tears. “She doesn’t deserve to be discriminated against.”

McCauley said Pan was “facilitating hate” against those who choose not to vaccinate their children, and she accused Brown of refusing to meet with opponents.

“He signed this quick and dirty because he wants us to go away. We’re not going away,” she said. “We’re going to sue. I personally will take this all the way to the Supreme Court.”

Despite passionate opposition to the bill, a poll by the Public Policy Institute of California this month found support for mandatory vaccines from 67 percent of California adults and 65 percent of public school parents.

Brown’s signature was expected. His office said earlier this year that Brown considered vaccinations “profoundly important,” and a senior adviser, though saying she was speaking on her own behalf, testified in favor of the measure.

Three years ago, however, in a relatively mild precursor to this year’s school vaccination bill, Brown made a special exemption for religious beliefs when he signed legislation requiring parents to consult a health professional before declining vaccinations for their schoolchildren.

In his signing statement Tuesday, the Democratic governor noted that the bill exempts children whose family medical histories lead a physician to recommend against immunization. But unlike in 2012, the former Jesuit seminarian said nothing about religion.