California vaccine laws are among the toughest in the nation, particularly since the state did away with the personal belief and religious exemption in 2015 following a measles outbreak that began in Disneyland. 

Governor Gavin Newsom signed a new law in September that gives the state stronger powers to reject suspicious medical exemptions for vaccines.

But both laws are complicated, and antivaccination parents and advocates continue to resist. Some mothers — most of them white, well-educated and affluent — refuse to vaccinate their children as they believe they should be the ones who make the medical decisions for their children; some parents don’t believe vaccines are safe.

Stanford Health Policy’s Michelle Mello, a professor of law and professor of medicine, writes in this Annals of Internal Medicine editorial that California’s experience is a cautionary tale about what happens when vaccination exemption laws have holes.

“The key lesson from California and beyond, therefore, is not that laws tightening vaccination exemptions are unhelpful, but that suboptimal policy design and political compromises may keep them from achieving all they can,” Mello writes in the editorial, which accompanies a wide-ranging assessment of exemptions from vaccination in California by Paul Delamater at the Carolina Population Center.

Delamater, an assistant professor of geography at the University of North Carolina at Chapel Hill, and a team at Yale University found that although the 2015 California law eliminating personal belief exemptions improved overall rates of vaccination in the state, its projected impact would be less than anticipated due to substitution of medical exemptions and other loopholes.

“Lawmakers should anticipate that antivaccination groups will mobilize to assist parents in identifying ways to get around new requirements,” Mello writes. In California’s case, the legislature had to go back to the drawing board to patch the holes, again confronting bitter resistance. Antivaxxers were so incensed by the new law that they threw blood on California senators during the final night of the legislative debate on Sept. 13.

“Avoiding repeated skirmishes requires getting it right the first time,” Mello writes. She recommends that laws narrowing vaccination exemptions include five key provisions:

1.     They should require that medical exemptions come from a pediatrician or family physician whom the child sees for regular care. 

“The physician evaluating whether a child has a medical condition that precludes vaccination should be someone who has been treating the child and is trained in a relevant specialty—not the anesthesiologist who lives next door or the physician hundreds of miles away who offers exemptions on the internet,” Mello said.

2.     They should limit the justifications for medical exemptions to valid, recognized contraindications to immunization.

3.     They should provide for review of medical exemptions by the department of health, as well as action against physicians who do not provide a specific and valid clinical rationale.

4.     The laws should clearly task the department of health — not schools — with reviewing exemptions.

5.     They should avoid grandfather clauses that allow children with existing conditions to forgo their vaccines. 

“Other states can also learn from what California did right,” Mello writes, such as jettisoning personal belief exemptions of all kinds and applying the rules to private schools and daycare centers as well as public ones.

California also makes public an expansive list of required immunizations and makes annual data on school-level exemption rates public.

“In the wake of the recent measles outbreak, state legislatures have been active in considering how to ensure that their laws are up to the challenge of preventing future outbreaks,” Mello writes in the editorial. “To be dispirited about the prospects for legal reform to help improve immunization rates is an empirical mistake. 

“The devil, as Delameter and colleagues show, is in the details.”