California lawmakers on Wednesday advanced a bill that would require schoolchildren in the state to be vaccinated amid impassioned pleas from parents and doctors, even activist Robert Kennedy Jr.

Under the proposal, parents would no longer be able to send unvaccinated kids to school with waivers citing religious or personal beliefs. Exemptions would be available only for children with health problems.

Supporters say the measure would increase the number of vaccinated young people and improve public health.

Ariel Loop told lawmakers that such a plan could have prevented her child from contracting measles at Disneyland. "My infant shouldn't have had to suffer. He shouldn't, still months later, be having complications with his eyes," she said. "I shouldn't have had to fear for his life."

Opponents, however, say vaccines can be as dangerous as the diseases they aim to fight and that the bill would trample parental rights.

Karen Kain said her daughter died of injuries from a mercury-tainted vaccine. "I stand here today before you to share my story so you can all see and hear what happens when vaccines go wrong," she said. "Who gets to make the choice now of whose babies are more important? Because there is risk, there must be choice."

The measure, SB277 from Sen. Richard Pan, was in the earliest stages of the legislative process. But it drew large crowds, including parents who brought their children. During the emotionally charged hearing, one opponent threatened to put a curse on lawmakers who voted for the bill and another woman was removed after an outburst.

The bill passed out of the Senate Health Committee on a 6-2 vote Wednesday.

If the bill passes the Legislature and signed by the governor, California would join Mississippi and West Virginia as the only states with such strict vaccine rules.

Similar efforts to reduce exemptions were proposed elsewhere after a measles outbreak in December that started at Disneyland and sickened more than 100 people across the U.S. and in Mexico. In Oregon and Washington state, however, such proposals were rejected recently.

Opponents include Kennedy, the nephew of President John F. Kennedy and son of former U.S. Attorney General Robert Kennedy.

Kennedy has been promoting the film "Trace Amounts" and is editor of a book called "Thimerosal: Let the Science Speak," linking autism to the vaccine preservative thimerosal. According to the federal Centers for Disease Control and Prevention, the mercury-containing chemical has been removed from routine childhood vaccines since 2001.

The Sacramento Bee reported that when Kennedy asked the crowd at a screening of the film on Tuesday how many parents had a child injured by vaccines, numerous hands went up.

"They get the shot, that night they have a fever of a hundred and three, they go to sleep, and three months later their brain is gone," Kennedy said. "This is a holocaust, what this is doing to our country."

At a rally ahead of Wednesday's legislative hearing, Kennedy said he had all six of his children vaccinated, but he remains concerned the pharmaceutical industry profits immensely when governments make vaccines mandatory.

Dr. Dean Blumberg, a pediatrician who testified on behalf of the American Academy of Pediatrics and the California Medical Association, said childhood vaccination has been so successful that it's easy to overstate their risks and dismiss the diseases they prevent.

"Unfortunately, there's much misinformation about vaccine safety and effectiveness," Blumberg said. "Let me be clear: There is no scientific controversy about vaccine safety and vaccine effectiveness. ... This is not open to dispute among mainstream doctors and scientists."

According to the National Conference of State Legislatures, California is among 20 states that allow for exemptions based on personal belief and 48 that allow for religious exemptions.

Public health officials believe an immunization rate of at least 90 percent is critical to minimizing the potential for a disease outbreak. California's kindergarteners met that threshold at the start of this school year, according to state statistics: 2 percent were exempted because of their parents' personal beliefs and another half a percent were exempted because of their parents' religion.