The 2016 California policy to eliminate nonmedical vaccine exemptions and changes in vaccine coverage: An empirical policy analysis

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dc.citation.articleNumbere1002994en_US
dc.citation.issueNumber12en_US
dc.citation.journalTitlePLOS Medicineen_US
dc.citation.volumeNumber16en_US
dc.contributor.authorNyathi, Sindisoen_US
dc.contributor.authorKarpel, Hannah C.en_US
dc.contributor.authorSainani, Kristin L.en_US
dc.contributor.authorMaldonado, Yvonneen_US
dc.contributor.authorHotez, Peter J.en_US
dc.contributor.authorBendavid, Eranen_US
dc.contributor.authorLo, Nathan C.en_US
dc.contributor.orgJames A. Baker III Institute for Public Policyen_US
dc.date.accessioned2021-10-19T15:35:29Zen_US
dc.date.available2021-10-19T15:35:29Zen_US
dc.date.issued2019en_US
dc.description.abstractBackground: Vaccine hesitancy, the reluctance or refusal to receive vaccination, is a growing public health problem in the United States and globally. State policies that eliminate nonmedical (“personal belief”) exemptions to childhood vaccination requirements are controversial, and their effectiveness to improve vaccination coverage remains unclear given limited rigorous policy analysis. In 2016, a California policy (Senate Bill 277) eliminated nonmedical exemptions from school entry requirements. The objective of this study was to estimate the association between California’s 2016 policy and changes in vaccine coverage. Methods and findings: We used a quasi-experimental state-level synthetic control analysis and a county-level difference-in-differences analysis to estimate the impact of the 2016 California policy on vaccination coverage and prevalence of exemptions to vaccine requirements (nonmedical and medical). We used publicly available state-level data from the US Centers for Disease Control and Prevention on coverage of measles, mumps, and rubella (MMR) vaccination, nonmedical exemption, and medical exemption in children entering kindergarten. We used county-level data individually requested from state departments of public health on overall vaccine coverage and exemptions. Based on data availability, we included state-level data for 45 states, including California, from 2011 to 2017 and county-level data for 17 states from 2010 to 2017. The prespecified primary study outcome was MMR vaccination in the state analysis and overall vaccine coverage in the county analysis. In the state-level synthetic control analysis, MMR coverage in California increased by 3.3% relative to its synthetic control in the postpolicy period (top 2 of 43 states evaluated in the placebo tests, top 5%), nonmedical exemptions decreased by 2.4% (top 2 of 43 states evaluated in the placebo tests, top 5%), and medical exemptions increased by 0.4% (top 1 of 44 states evaluated in the placebo tests, top 2%). In the county-level analysis, overall vaccination coverage increased by 4.3% (95% confidence interval [CI] 2.9%–5.8%, p < 0.001), nonmedical exemptions decreased by 3.9% (95% CI 2.4%–5.4%, p < 0.001), and medical exemptions increased by 2.4% (95% CI 2.0%–2.9%, p < 0.001). Changes in vaccination coverage across counties after the policy implementation from 2015 to 2017 ranged from −6% to 26%, with larger increases in coverage in counties with lower prepolicy vaccine coverage. Results were robust to alternative model specifications. The limitations of the study were the exclusion of a subset of US states from the analysis and the use of only 2 years of postpolicy data based on data availability. Conclusions: In this study, implementation of the California policy that eliminated nonmedical childhood vaccine exemptions was associated with an estimated increase in vaccination coverage and a reduction in nonmedical exemptions at state and county levels. The observed increase in medical exemptions was offset by the larger reduction in nonmedical exemptions. The largest increases in vaccine coverage were observed in the most “high-risk” counties, meaning those with the lowest prepolicy vaccine coverage. Our findings suggest that government policies removing nonmedical exemptions can be effective at increasing vaccination coverage.en_US
dc.identifier.citationNyathi, Sindiso, Karpel, Hannah C., Sainani, Kristin L., et al.. "The 2016 California policy to eliminate nonmedical vaccine exemptions and changes in vaccine coverage: An empirical policy analysis." <i>PLOS Medicine,</i> 16, no. 12 (2019) Public Library of Science: https://doi.org/10.1371/journal.pmed.1002994.en_US
dc.identifier.digitalpmed-1002994en_US
dc.identifier.doihttps://doi.org/10.1371/journal.pmed.1002994en_US
dc.identifier.urihttps://hdl.handle.net/1911/111573en_US
dc.language.isoengen_US
dc.publisherPublic Library of Scienceen_US
dc.rightsThis is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.en_US
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/en_US
dc.titleThe 2016 California policy to eliminate nonmedical vaccine exemptions and changes in vaccine coverage: An empirical policy analysisen_US
dc.typeJournal articleen_US
dc.type.dcmiTexten_US
dc.type.publicationpublisher versionen_US
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