Lawmakers in California have taken an important first step toward limiting vaccination exemptions for schoolchildren. The bill, which was approved on Thursday, prohibits parents from preventing their children from being vaccinated for personal or religious reasons.

The bill – SB 277 – makes California the third state to remove religious and personal vaccine exemptions. It follows the recent Measles outbreak in Disneyland, which spread and sickened nearly 150 people in the United States. The outbreak was traced back to an infected person that visited the amusement park, and spread rapidly mainly by children whose parents chose not to vaccinate them, a study concluded.

"Do we wait until we have a full-fledged crisis to protect the most vulnerable?" asked Assemblywoman Lorena Gonzalez, the Associated Press (AP) reports.

The legislation was approved in a 46-30 vote in the California Assembly. The Senate, who have already approved the bill, must now sign off on some amendments before the bill is sent to Governor Jerry Brown. Though the governor hasn’t indicated whether he will sign the bill, the L.A. Times reports that a spokesperson has said: "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." If passed, the law will come into effect on January 1, 2016.

Medical reasons, including allergic responses and weak immunity, will be the only exemption parents wanting to register their children in preschool and kindergarten can use. The law also states that children are not allowed to progress to the seventh grade without the required immunization. The bill does not affect home-schooled children.

“We hope and expect we will be a model to get us back to where we should be, which is that cases of measles and other preventable diseases do not need to be something we live with,” said State Senator Richard Pan, a pediatrician who wrote the bill, The New York Times reports.

Though the bill received bipartisan support, there was significant opposition from parents – many of whom gathered on the Capitol steps to protest the vote. Reuters reports that Senator Pan had to be given extra security as he received death threats from vaccination opponents.

"People in the opposition say they want children to get these diseases naturally," Pan said. "But children die of these diseases. They become paralyzed. They develop brain damage. This is not something I would wish on anybody's child."

Those supporting the bill ensured their voices were also heard. Rhett Krawitt, a seven-year-old leukemia survivor, delivered a petition with over 30,000 signatures to the governor on Wednesday. His parents were nervous to enroll him in school as he cannot be vaccinated for a year after receiving chemotherapy.