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Measles Outbreak

End of Opt Out? California Bill Would Tighten Vaccination Rules

Image: Immunization drive against measles, mumps and rubella

Jacqueline Fletcher, director of family and community health services at the Knox County, Ohio Health Department, prepares doses of the measles, mumps and rubella (MMR) vaccine. Noah Addis / for NBC News

California lawmakers have proposed making it harder for parents to opt out of vaccinating their children.

Their bill in the state senate would tighten up California’s personal philosophy exemption that some critics say makes it too easy for parents to skip vaccines without a medical or sincere religious belief. Under the bill, parents still would be allowed to forgo vaccinations if immunizations pose a medical risk to their children.

“We do not need to wait for a child to sicken or die before we act. And that’s what we’re doing here today,” said Democratic state senator Richard Pan, who is a pediatrician. Pan and fellow state senator Ben Allen, a Democrat, are sponsoring the bill.

“We do not need to wait for a child to sicken or die before we act."

California health officials released new statistics Wednesday that show 99 people have been reported with measles, most linked to an outbreak that started at Disneyland. The outbreak, which has spread to at least 14 states and Mexico, has ignited a fierce debate about what to do about people who choose not to vaccinate themselves or their children.

Public health experts say when people aren’t vaccinated, it allows infections such as measles to circulate and take hold. Centers for Disease Control and Prevention Director Dr. Tom Frieden told NBC News he’s worried measles could take hold in the U.S.

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California’s two U.S. senators, Barbara Boxer and Dianne Feinstein also have suggested big changes to California’s decades-old exemption statute. They wrote to state health officials asking them to have another look at the policy.

"While a small number of children cannot be vaccinated due to an underlying medical condition, we believe there should be no such thing as a philosophical or personal belief exemption, since everyone uses public spaces," Boxer and Feinstein, who are both Democrats, wrote.

"As we have learned in the past month, parents who refuse to vaccinate their children not only put their own family at risk, but they also endanger other families who choose to vaccinate."

A study published last month in the journal Pediatrics found pockets of under-vaccinated kids in parts of California.

"Parents who refuse to vaccinate their children not only put their own family at risk, but they also endanger other families who choose to vaccinate."

For instance, 17.9 percent of children in Marin County, north of San Francisco, hadn’t received all the recommended vaccines between 2010 and 2012. And in one part of Vallejo, also in the Bay Area, 22.7 percent of kids were under-vaccinated. More than 7 percent of the parents of babies and toddlers in San Francisco had refused all vaccines, and in one area near Sacramento, 13.5 percent of these young children had not been vaccinated at all.

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These are the kinds of clusters that can allow outbreaks to take hold. Measles is extremely contagious and 90 percent of unimmunized people exposed to the virus will become infected.

California's not the only state with the problem. Colorado has the highest rates of under-immunized children, according to the Centers for Disease Control and Prevention.