Garnier Romain, Nedell Emma R, Omer Saad B, Bansal Shweta
Department of Biology, Georgetown University, Washington, District of Columbia, USA.
Yale Institute for Global Health, Yale University, New Haven, Conneticut, USA.
Open Forum Infect Dis. 2020 Mar 14;7(3):ofaa088. doi: 10.1093/ofid/ofaa088. eCollection 2020 Mar.
State-mandated school entry immunization requirements in the United States play an important role in achieving high vaccine coverage, but variations in vaccine exemption policies result in a patchwork of vaccine coverage across the country.
In this study, we evaluate epidemiological effects and spatial variations in nonmedical exemption (NME) rates in the context of vaccine policies. We first analyze the correlation between NME rates and vaccine coverage for 3 significant childhood vaccinations. Furthermore, we assess the effects of policy changes in a subset of states, using a correlative approach at the state level and performing a clustering analysis at the county level.
We find that higher rates of exemptions are associated with lower vaccination rates of school-aged children in all cases. In a subset of states where exemption policy has recently changed, we show that the effects on statewide NME rates vary widely and that decreases in NMEs can lead to an increase in other types of exemptions. Finally, our clustering analysis in California, Illinois, and Connecticut shows that policy changes affect the spatial distribution of NMEs.
Our work suggests that vaccination policies have significant impacts on patterns of herd immunity. Our findings can be used to develop evidence-based vaccine legislation.
美国各州规定的入学免疫要求在实现高疫苗接种覆盖率方面发挥着重要作用，但疫苗豁免政策的差异导致全国疫苗接种覆盖率参差不齐。
在本研究中，我们在疫苗政策背景下评估非医学豁免（NME）率的流行病学影响和空间差异。我们首先分析了3种重要儿童疫苗接种的NME率与疫苗接种覆盖率之间的相关性。此外，我们使用州级相关方法并在县级进行聚类分析，评估了部分州政策变化的影响。
我们发现，在所有情况下，豁免率较高都与学龄儿童较低的疫苗接种率相关。在最近豁免政策发生变化的部分州，我们表明对全州NME率的影响差异很大，NME率的下降可能导致其他类型豁免的增加。最后，我们在加利福尼亚州、伊利诺伊州和康涅狄格州的聚类分析表明，政策变化会影响NME的空间分布。
我们的研究表明，疫苗接种政策对群体免疫模式有重大影响。我们的研究结果可用于制定基于证据的疫苗立法。
