The bill, which would make California the third state to eliminate religious and other personal vaccine exemptions, passed the state Assembly in a form that would give some parents years to comply, compared with a stronger version of the bill that was earlier approved by the state Senate.
The measure sparked angry opposition from parents who fear side effects from vaccinations as well as from some religious conservatives.
In testimony on the bill, opponents said they feared their children would be harmed and that the bill would deny them their right to public education.
In recent years, vaccination rates at many California schools have plummeted as parents, some of whom fear a now debunked link between vaccines and autism, have declined to inoculate their children.
Most children are vaccinated, but at some schools, many in affluent and liberal enclaves, vaccination rates are well below the 92 percent level needed to maintain group immunity that can protect those who are not vaccinated or have weak immune systems.
The legislature had to increase security for one of the bill’s main authors, Democratic Senator Richard Pan of Sacramento, after he received death threats from vaccine opponents.
Pan, a pediatrician, outraged vaccine opponents three years ago when he carried a successful bill to require parents to consult with a medical professional before they could receive a personal beliefs exemption. But he said this time opposition was even more vociferous, surprising many in the legislature and making the bill’s success uncertain for a time.
“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.”
Under the bill, which now goes back to the Senate for approval of amendments, unvaccinated children without a medical exemption would have to study at home or in organized, private home-schooling groups.