With the ongoing measles outbreak in Washington, there has been increasing national attention to real-life consequences of vaccine-preventable diseases and vaccine hesitancy. Most of cases in this recent outbreak have been among unvaccinated individuals and children between the ages of 1 and 10 years. In the first month of 2019, the US has already seen 101 measles cases, on pace to exceed the 372 cases in 2018 and 120 cases in 2017.

Studies have shown that states that have more lenient immunization laws generally have higher nonmedical exemption and disease rates compared to states with stricter exemption laws.

With measles cases popping up all over the country from Washington to Texas to New York, state lawmakers are considering stricter immunization exemption laws in New York, New Jersey, Vermont, Washington, and Oregon, among others. For example, in Washington, lawmakers have introduced a bill to remove the option for parents to claim personal belief exemptions for MMR (measles, mumps, rubella) vaccine; however, the proposed bill does not remove the religious exemption option. In Oregon, where cases from the Washington outbreak are spilling over, lawmakers are proposing a bill to eliminate all nonmedical exemptions (personal belief and religious) for school entry and child care facilities.

States considering removing all nonmedical exemptions can look to three states for guidance (West Virginia, Mississippi and California). However, California provides the most useful example as it was the first state in nearly 35 years to pass a strict law, giving us a contemporary and unique landscape to examine the impact of removing nonmedical exemption laws.

Shortly after a large-scale measles outbreak that originated in Disneyland in December 2014, the California state assembly passed Senate Bill 277 (SB277), a law eliminating personal belief exemptions for school entry. The goal of SB277 is to increase the number of children who are up to date on their immunizations. While it is still too early to see the law’s full impact, a lot has happened in its first two years. Let’s take a look.

The passage of SB277 was met with resistance. California’s highly engaged and mobilized anti-vaccine groups filed multiple lawsuits opposing the law. The lawsuits claimed that SB277 violates parental rights, rights to education, religious freedom, and more. Two state trial courts, three federal district courts, and two California Courts of Appeal have all rejected challenges to SB277. Since SB277’s implementation, the rate of kindergarten students receiving all required vaccines has increased from 92.8% in 2015-16 to 95.1% during the 2017-18 school year. This is promising.

Not all the movement has been in the right direction, though; California also saw a large increase in rates of permanent medical exemptions, from 0.2% in 2015-16 to 0.7% in 2017-18 and the rates are even higher in private schools (2.1%) compared to public schools (0.6%). Medical exemptions are meant for children who have rare medical conditions, so some increase – fueled by children with real medical contraindications whose parents previously used the easier personal belief exemption – was to be expected, but the dramatic increase goes beyond that. While 0.7% may seem like a small percentage, it represents a 250% increase from the previously low rates of medical exemptions, which had remained below 0.2% for the previous six years. The increase is worrisome, because it suggests that certain portions of California are still susceptible to vaccine-preventable outbreaks.

So what’s going on here? Counties that had high personal belief exemption rates before SB277 saw the largest increases in medical exemptions, suggesting a possible substitution/replacement effect. It could be that vaccine-hesitant parents who previously had personal belief exemptions for their children are seeking out doctors who will write unwarranted medical exemptions. A recently published article in Pediatrics highlighted several examples of physicians charging fees in exchanging for granting medical exemption requests. Another recent article in the American Journal of Public Health pointed to the vague regulatory language surrounding the type of physicians who can write medical exemptions, the medical conditions that are valid contraindications for immunizations, and the process for reporting questionable medical exemptions as reasons for wanting a central state-level review of medical exemptions.

California passed Senate Bill 277 in response to years of ongoing vaccine-preventable disease outbreaks and the Disneyland measles outbreak. States like Oregon and Washington are now in a similar position: if they are able to follow through with implementing stricter immunization laws to curb the occurrence of vaccine-preventable disease outbreaks, these states can learn from what has happened in California so far. Laws like SB277 can help prevent outbreaks, and are constitutional, but it is important to keep an eye out for loopholes. While stricter immunization legislation can increase uptake, it still leaves the potential for clusters of undervaccinated and unvaccinated children. Continued vigilance is warranted.

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This work was supported by an LDI Policy Accelerator Grant to LDI Associate Fellow Salini Mohanty. Her co-author, Dorit Rubinstein Reiss, is a Professor of Law at UC Hastings.