AMHERST, Mass. – An analysis of policy research on nearly 50 years of school vaccine mandates has found that while vaccine requirements are commonly considered to have made a major, if not essential, contribution to vaccine coverage in the United States, the causal relations between mandates and population vaccination remains unclear. The findings were published online this week by the Canadian Medical Association Journal’s CMAJ Open.
The team of researchers, led by Devon Greyson, assistant professor of communication at the University of Massachusetts Amherst, investigated the findings of 20 studies that looked at two forms of mandates, school-entry mandates (from 1970-2017) and adolescent, or “middle school,” mandates from the 1990s to 2015. Eighteen of the studies, including all of the adolescent mandate research, were set in the U.S., and two school-entry mandate studies were set in Italy and Australia, respectively.
They found that while adding well-accepted vaccines to an existing mandate is usually associated with increased vaccination, it is unclear to what extent such increases are due to the compulsory nature of the policies or to co-interventions that increase access and awareness.
“Few studies examined or accounted for the influence of common co-interventions such as improved access, education, insurance coverage, and changes in vaccine purchasing or costs,” write Greyson and co-authors Chris Vriesema-Magnuson, of the University of British Columbia, and Julie A. Bettinger, from the BC Children’s Hospital Research Institute. “Furthermore, implementation and enforcement of vaccine mandates were not examined in most studies, yet poor implementation and/or uneven enforcement may render a policy ineffective.”
“Vaccines are an important tool for keeping the community healthy,” Greyson says. “For most diseases, we need almost everyone to receive the vaccine in order to protect vulnerable community members such as babies and people with compromised immune systems. One approach to encouraging community vaccine coverage is to require that school children show proof of vaccination, with policies commonly called mandates.
“There are hints in the evidence that context and details matter a lot to how a vaccination mandate works out, though,” she cautions. “This means there’s not one universal answer to this question—what works in one place and time may backfire in another. There are theoretical risks to mandate policies, such as clustering of unvaccinated children, for example in private or home schooling, or in geographic areas where mandates don’t exist or aren’t enforced, which could lead to outbreaks even if exemptions are low and overall population coverage is high. Luckily, some newer studies are currently starting to investigate these important questions.”
The studies reviewed by the researchers showed that new or tightened requirements for vaccination of schoolchildren were usually associated with increased coverage of the affected populations, with effects appearing larger when pre-intervention vaccination rates were low. However, the authors of the new report also point out that the mandates for HPV (human papillomavirus) vaccination in the U.S., where there was a high degree of population hesitancy and politicization around the vaccine, were notably ineffective.
In light of the HPV mandates’ failures, the authors conclude that “owing to the risk of backlash, in cases of highly politicized vaccines or in jurisdictions without a tradition of mandates, other approaches such as improving access, education and documentation might be tried before moving to mandated vaccination.”
“When we first started using mandates, it was hard to study their precise effects,” Greyson says. “Now our data systems are much more advanced, and we can better investigate the details of what does and doesn’t work about a new policy. I do think that data mandates are universally a fairly good idea, although we should have integrated immunization systems so schools and public health agencies know who is at risk when there are disease outbreaks. Such a system would also provide researchers with a more powerful tool to more fully understand the best use of public policy to further encourage vaccination.”
The complete report, “Impact of school vaccination mandates on pediatric vaccination coverage: a systematic review,” can be found at here.