The 50-state Laboratory: How Can Behavioral Science Bolster Vaccination Policy?

Vaccinating kids saves a lot of lives and a lot of dollars. High rates of vaccine coverage assure community protection (“herd immunity”), and in the United States we achieve this by requiring children to be fully vaccinated by the time they start school. Taken together, these requirements are often called the “immunization schedule.” We’ve mandated school-entry immunization for so long that it at times seems like a given, but many other countries don’t have similar mandates. They suffer from lower vaccine coverage and more disease.

But what happens when parents in the U.S. don’t want their children to be vaccinated? All 50 states have legalized medical exemptions: Some kids, due to medical contraindications like immunosuppression or severe allergy, cannot safely be vaccinated. Most states also make some provision for nonmedical exemptions: These might be religious, philosophical, or “personal belief” objections to the required immunization schedule.

School-entry mandates and exemptions from those mandates are determined by states, so we essentially have a 50-state laboratory for studying the effects of exemption laws on parent responses, vaccine coverage, and disease outbreaks. In recent years, parents have been increasingly hesitant to vaccinate their children, and outbreaks of vaccine-preventable diseases have risen. (Remember the Disneyland measles outbreak?) In response, many states are rethinking when and how they allow vaccine exemptions.

Vaccine exemption law is fertile ground to apply behavioral science to public policy.

In 2017, 17 states considered more than 40 changes to their state’s exemption regime. Were behavioral insights in evidence in most of these proposed bills? A little bit. Could there be more? For sure. Vaccine exemption law is fertile ground to apply behavioral science to public policy. Below are four behavioral principles relevant to exemption legislation, along with some examples of current and proposed exemption laws that leverage these insights:

#1: Add hassle factors

Many proposed revisions invoke the idea of making easier to adhere to immunization schedules (opting in) than to get an exemption (opting out). This makes sense: We know from prior studies that states with tougher exemption requirements (for instance, needing a health care provider to sign the exemption form versus the parent just signing the form themselves) have lower exemption rates. In the 2017 legislative session, Iowa proposed that religious exemption seekers provide an affidavit signed by the applicant’s religious leader confirming that immunization conflicts with specific religious tenets. This should prevent people from abusing the religious exemption to circumvent vaccine mandates.

Minnesota proposed several additional requirements for exemption. These include a statement from the child’s physician confirming the applicant and guardian have received information about the health risks of failing to vaccinate and an acknowledgement that the student may be prohibited from attending school in the case of an outbreak. This last requirement is particularly good at making the benefits of vaccination salient—it helps the parent visualize a future exclusion from school.

If some hassle is good, is more hassle better? Idaho currently requires parents to write a short statement explaining or justifying their exemption request. My research team hypothesized that while this might add some hassle factor, the act of writing the statement might equally serve to reinforce anti-vaccine beliefs (and we’re testing that in an online experiment; stay tuned for the results). How about the ultimate hassle: No nonmedical exemptions at all? This was proposed in the Arizona legislature, and was actually passed and implemented in California following the Disneyland outbreak. This might not work, due to increased reactance to this issue when the nonmedical exemption option is withdrawn altogether.

#2: Design incentives for maximum impact

Much of the recent work on behavioral economics and health has focused on optimally designed incentives (financial and non-financial) for healthy behaviors. Could this work in exemption laws? One of several proposed bills in the New York state legislature would eliminate the dependent tax deductions for taxpayers who fail to comply with immunization requirements for their dependents (with the savings going to the Department of Health for vaccine education).

The problem here is a licensing effect. Once parents can effectively “pay to not play,” exemption become more of a consumer choice than a moral obligation. And are parents the right place to apply incentives (whether carrots or sticks)? Insurance companies already reward physician practices (through quality bonuses) for vaccine coverage rates in their patient panels. Exemption laws could build in similar rewards for school districts that reduce exemption rates or maintain low or zero exemption rates over time.

#3: Make vaccine education count

Educating parents about the benefits of vaccination and the harms of not vaccinating has long been promoted as a key strategy to promote vaccine acceptance—with little evidence to support its effectiveness. Optimism about vaccine education is evident in a proposed bill in Connecticut, requiring parents who seek an exemption to provide evidence of participation in a “science-based” education module. (Washington state already requires this; you can complete their required education module yourself here).

A required education module can serve as an effective hassle factor, but in order to actually persuade a vaccine-hesitant parent to get their kid vaccinated and not require an exemption, the educational content needs to be “behavioral science-based.” How? One strategy is to increase the salience of the real risks of contracting vaccine-preventable diseases. This can help counter risk compensation (parents don’t think their kid will contract a vaccine-preventable disease) and ambiguity aversion (parents prefer known risks of not vaccinating to unknown risks of vaccinating). However, increasing the salience of the potential harm (versus risk) of vaccine-preventable diseases may backfire with vaccine-hesitant parents. A lot more research is needed on when the backfire effect kicks in and how to avoid or circumvent it.

#4: Leverage social norms and peer pressure

Fortunately, the vast majority of parents fully vaccinate their kids. Exemption rates are low in many schools, districts, counties, and states. Exemption laws can leverage this strong social norm by making exemption data publicly available and by mandating school-level reporting. A proposed law in Texas requires school districts to report data on requested, granted, and denied exemptions to the state’s Department of Health, which will make the data public on the department website. Schools also must notify parents and guardians upon request if any student in the school is exempted. New York proposed a similar reporting requirement. In addition to confirming the social norm for complete vaccination, these publicly available data also permit the identification of exemption outliers or “hotspots.” As with educational interventions and incentives, some caveats about licensing and backlash are warranted.

Our 50-state laboratory will gear up again in the next legislative sessions—that’s good news for public health and policy researchers interested in conducting observational studies of changes in state exemption laws. But there’s also an opportunity to be more proactive: Legislative staff can deploy evidence from behavioral science when drafting new exemption laws. My research team and I are busy drafting evidence-based model legislation templates so that legislators don’t have to start from scratch when designing new exemption laws. We hope to push the field from outdated, ineffective, or politically-motivated approaches to crisp, simple legislative strategies that use behavioral insights to keep kids healthy.

Further Reading & Resources

  • Opel, D. J., & Omer, S. B. (2015). Measles, mandates, and making vaccination the default option. JAMA pediatrics169(4), 303-304. (Link)
  • Buttenheim, A. M. (2017). The vaccination-exemption challenge. Governing. (Link)
  • Buttenheim, A. M., & Asch, D. A. (2016). Leveraging behavioral insights to promote vaccine acceptance: One year after Disneyland. JAMA pediatrics170(7), 635-636. (Link)
  • Buttenheim, A. M. Don’t expect a ‘Disneyland effect.’ Health policy$ense: The blog of the Leonard Davis Institute of Health Economics. (Link)
  • Association of State and Territorial Health Officials. (2017). State legislative tracking. (Link)