California law cracking down on vaccine exemptions may have modest results
Despite a 2015 law banning personal belief vaccine exemptions for children entering California schools, the rate of exemptions is expected to decrease only slightly in the state by 2027, according to a study published in the Annals of Internal Medicine.
A previous study published in JAMA showed that Senate Bill 277 (SB277), combined with education efforts, had an immediate impact on rates of undervaccinated kids entering kindergarten. However, another study published in Pediatrics showed that the rate of medical vaccine exemptions in the state increased in the 3 years after the bill was passed — suggesting a “replacement effect,” according to researchers.
Paul L. Delamater, PhD, an assistant professor in the department of geography at the University of North Carolina at Chapel Hill, and colleagues explained that certain provisions “limit the bill's effectiveness, including grandfathering of pre-SB277 nonmedical exemptions, exemption of homeschooled children and those not in classroom-based environments from vaccination requirements and relaxation of allowable medical exemption criteria.”
Researchers reviewed school enrollment and vaccination data for 2009 to 2018 from the California Department of Public Health and the projected kindergarten enrollment data for 2019 to 2027 released by the state’s department of education.
Delamater and colleagues projected the impact of vaccine exemptions based on three scenarios. The first assumed that those with a vaccine exemption would continue to use it throughout their schooling, the second estimated the effects of another bill passed by the state in 2019 with stricter definitions of medical exemptions (SB276) if it was enforced in 2020, and the third projected vaccine the rate of exemptions if SB277 and SB276 had not been passed.
Based on current exemption use, the rate of exemptions decreased by just 0.72% from the level of vaccine exemptions before SB277 was passed, stabilizing at 1.87% among California schoolchildren.
In the scenario that included the enforcement of SB276, the percentage of students with any vaccine exemption decreased from 2.19% in 2018 to 1.41% in 2027.
Without SB277 or SB276, the percentage of kids with any type of vaccine exemption began to decrease in 2018 and will stabilize in 2021 at 2.36%.
The findings suggest that even with the introduction of SB277, the vaccine exemption rate would stabilize at 1.87%, a slight decrease from the rate of 2.59% before the legislation was passed. Based on these projections, the rate of vaccine exemptions in 2027 will be only 0.49 percentage points lower than if SB277 was never passed.
In an editorial accompanying the study, Michelle M. Mello, JD, PhD, a professor of law at Stanford Law School and a professor of medicine at Stanford University, explained that the lesson from these findings 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.”
She noted that laws should require medical exemptions to come from a child’s primary care physician, limit exemptions to valid contraindications for immunization, require the department of health to review exemptions and take action against physicians who do not provide a valid reason for exemption. In addition, she called for future laws to require the department of health to review exemptions rather than individual schools and urged lawmakers to avoid grandfather clauses. – by Erin Michael
Disclosures: Delamater reports receiving grants from the NIH during the conduct of the study. Please see the study for all other authors’ relevant financial disclosures. Mello reports no relevant financial disclosures.