SACRAMENTO (CBS SF) — Security has been stepped up at the state capitol Tuesday night after the author of a bill that would make it harder for parents to opt out of vaccinations for their children received death threats.

Senate Bill 277 hits a Senate committee Wednesday, a bill that would end the personal belief exemption for parents.  The threats are against State Senator Dr. Richard Pan, the bill’s author.

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The California Highway Patrol, which is in charge of security at the capitol has stepped up its efforts after Dr. Pan received threats through email and Facebook.  At least one post referred to Dr. Pan as Hitler.

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Dr. Pan wasn’t commenting on the recent threats, but last week spoke about parents threatening to pull their children out of school if the bill passes.

“It seems to be another tactic by the opposition that’s based on exaggeration and intimidation.  I think the people who are most knowledgeable about this subject are in support of this bill,” Dr. Pan said.

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It is believed that un-vaccinated children represent about one to five percent of California’s public school attendees.