SACRAMENTO — The author of California legislation to require state approval of all childhood vaccination exemptions pulled back Tuesday after Gov. Gavin Newsom said the measure would inject government bureaucracy into doctor-patient decisions.

State Sen. Richard Pan, D-Sacramento, who proposed the legislation, unveiled amendments that would limit the number of medical exemptions that would have to be approved by the state Department of Public Health. Even with the amendments, however, tens of thousands of existing student exemptions could be subject to state review.

Opponents of mandatory childhood vaccinations said they would continue to fight the bill, maintaining it would criminalize doctors who protect children from what the opponents say are vaccines’ potential side effects.

Pan, a pediatrician, said the amendments to his SB276 were the result of negotiations with the Newsom administration. He said the revamped bill would allow for legitimate medical waivers while cracking down on doctors who issue inappropriate exemptions, creating the risk of a disease outbreak.

“I appreciate that the governor has worked with me in crafting a California solution to halting the abuse of medical exemptions that endanger our children,” Pan said in a statement. “The governor recognizes that we need to ensure that children who truly need medical exemptions get them and they will be safe in their schools with community immunity.”

SB276, as originally drafted, would require the state Department of Public Health to approve every request for a medical exemption to a child’s immunization schedule — taking the sole power to grant a waiver away from individual doctors.

Newsom had said he had “concerns about a bureaucrat making a decision that is very personal.” Although he didn’t explicitly say he would veto SB276, his comments put the bill’s fate in jeopardy.

On Tuesday, the governor said he was “very pleased” with the proposed amendments and will sign SB276 if it passes the Legislature with the changes intact.

“We’ve worked very closely with the senator,” Newsom said. “This will make it workable and I think addresses some of my bureaucratic anxieties, which was the core of my previous comments.”

The bill is scheduled to be heard in an Assembly committee Thursday. The Senate has already approved the original measure, and would have to vote again on the amended bill if the Assembly approves it.

Pan’s amendments would require state public health officials to conduct a review if a public school has an immunization rate less than 95%, the threshold for “community immunity,” or an individual doctor grants more than five exemptions in a calendar year. The state could revoke exemptions that it finds are fraudulent or inconsistent with medical guidelines.

A parent or guardian would have the right to appeal an exemption denial, and a panel of doctors would review the appeal. The state health and human services secretary would make the final decision.

Pan’s amendments could still leave many exemptions facing state review. There are 835 schools in California that have immunization rates of less than 95%, the Health Officers Association of California said in an April report. The group, which represents city and county health officers, listed scores of Bay Area schools with less than 95% immunization.

California requires schoolchildren to be inoculated against infectious diseases including measles, mumps, chicken pox, tetanus, whooping cough and rubella.

If Pan’s amended bill becomes law, parents or guardians of children exempted from the vaccines before Jan. 1, 2021, would have to submit a copy of the exemption to the state for it to remain valid.

The state would have the authority to revoke an exemption if a local public health official determined it was fraudulent or inconsistent with medical guidelines. The guidelines would be criteria outlined by the federal Centers for Disease Control and Prevention, Advisory Committee on Immunization Practices or American Academy of Pediatrics.

The state formerly allowed parents to exempt children based on personal beliefs, but repealed that exception in a Pan-sponsored 2015 bill after an outbreak of measles was traced to visitors at Disneyland who had not been immunized. California now requires a doctor to approve any exemption.

Since the law took effect, the number of kindergartners entering school with medical exemptions has more than tripled.

Pan said SB276 is necessary to crack down on doctors who sell fraudulent medical exemptions to parents. He said unethical physicians have sought to make a profit.

His amendments would require doctors to use a standard exemption form and attest, under penalty of perjury, that the patient’s medical information is accurate. Pan also proposes to punish unscrupulous doctors by banning them from submitting exemptions for at least two years, if the state Department of Public Health determines the physician poses a risk to health in a community.

Opponents of vaccinations took to social media Tuesday to blast the proposed amendments. Californians for Vaccine Choice tweeted that the changes seek to criminalize doctors who know that vaccines might harm a child.

Debra Schaefer, a mother of three from Orange County, opposes Pan’s bill, including the amendments, because she said it would make exemptions too restrictive. She said her 5-year-old daughter, who starts kindergarten this year, suffered severe neurological and muscular problems after she received vaccinations as a toddler, but wouldn’t qualify for a waiver under SB276.

“We would be homeschooling,” Schaefer said, adding that her family has a history of autoimmune issues. “This is not going to solve the problem here, going after these medically fragile children.”

Critics of the bill have launched a recall campaign against Pan. A similar recall effort against the lawmaker fizzled in 2015.

SB276 has also drawn opposition from a few celebrities critical of mandatory vaccinations. Actress Jessica Biel and activist Robert F. Kennedy Jr. traveled to Sacramento last week to lobby lawmakers against the bill.

Kennedy leads a group that says vaccines are tied to autism and other medical conditions. Those assertions have been forcefully rejected by the Centers for Disease Control and Prevention and major medical organizations, which report there is no link between vaccines and autism.

After facing criticism, Biel posted on Instagram that she’s not anti-vaccine but supports “families having the right to make educated medical decisions for their children alongside their physicians.”

San Francisco Chronicle staff writer Bob Egelko contributed to this report.

Dustin Gardiner is a San Francisco Chronicle staff writer. Email: dustin.gardiner@sfchronicle.com Twitter: @dustingardiner