Application of Branching Processes to Measles in California

项目总结/摘要 麻疹是一种高度传染性的病毒性疾病，2000年在加州被宣布消灭， 美国成功的疫苗接种计划。然而，麻疹仍然是一个公共卫生问题， 加州：麻疹疫情继续以小规模聚集、传播链或孤立病例的形式发生， 从地方病流行区引进。每个病例的公共卫生资源总额约为10万美元， 从其他公共卫生项目中抽调资金用于监测疫情和调查病例接触者。有组织 反对接种疫苗是控制麻疹的关键组成部分，这仍然是一个重大关切。 一场与迪斯尼乐园主题公园有关的大规模疫情，其中131名加利福尼亚人被感染， 2015年初的头条据推测，这次异常大的疫情是由于疫苗接种减少所致 由于反对接种疫苗，事实上，目前尚不清楚为什么有些疫情比其他疫情大。 加州公共卫生部的流行病学家观察到， 应变倾向于大于其它应变。已观察到传输的差异， 接种疫苗和未接种疫苗的病例，并可能解释观察到的暴发规模的异质性。此外，本发明还提供了一种方法， 一年中的某些时间可能更容易传播。 这个项目的目标是利用麻疹的数据来确定为什么有些疫情比其他疫情大 加州公共卫生部从2000年到2015年在加州的病例，通过两个 具体目标：我们的目标是确定（目标1）是否有证据表明B3麻疹毒株更具传播性 以及（目的2）未接种疫苗的个体的聚集是否解释了为什么意外的大 麻疹爆发。所提出的技术包括分支过程理论，其可用于 提供控制程度的直接估计和因果推断，以帮助协变量选择。两 将使用最大似然和模拟技术，沿着使用混合效应模型和参数 自力更生如果某些菌株更具传播性，或者如果未接种疫苗的个体聚集在一起， 爆发规模，接触调查策略可以修改，以提高效率。此外，结果 可以用来为全国的疫苗接种政策提供信息。 拟议的培训计划包括实践研究经验，以执行拟议的目标和实现 申请人的论文要求。培训还将包括加州大学旧金山分校和加州大学的高级课程 加州，伯克利和指导阅读与赞助商（教授特拉维斯波尔科）和共同赞助商 （韦恩·伊纳诺里亚教授）。额外的培训和指导将来自詹妮弗·齐普里希博士， 加州公共卫生部免疫分支和论文委员会的流行病学家 成员，教授玛丽亚Gadriour（加州大学旧金山分校）和教授Jamie Gadrid-Smith（加州大学洛杉矶分校）。

PROJECT SUMMARY/ABSTRACT Measles, a highly contagious viral illness, was declared eliminated in 2000 in California as a result of a successful vaccination program in the United States. However, measles remains a public health problem in California: Measles outbreaks continue to occur as small clusters, transmission chains, or isolated cases due to introductions from endemic areas. Public health resources totaling approximately $100,000 per case are diverted from other public health programs to monitor outbreaks and investigate contacts of cases. Organized opposition to vaccination, the key component of measles control, remains a significant concern. A large outbreak linked to Disneyland theme parks, in which 131 Californians were infected, made international headlines in early 2015. It was speculated that this unusually large outbreak was due to decreased vaccination rates as a result of opposition to vaccination. In fact, it is not clear why some outbreaks are larger than others. Epidemiologists at the California Department of Public Health have observed that outbreaks of the B3 measles strain tend to be larger than those of other strains. Differences in transmission have been observed for vaccinated and unvaccinated cases and may account for observed heterogeneity in outbreak size. In addition, certain times of year may be more permissive for transmission. The goal of this project is to determine why some outbreaks are larger than others using data on measles cases in California from 2000 to 2015 from the California Department of Public Health, achieved through two specific aims: we aim to determine (aim 1) if there is evidence that the B3 measles strain is more transmissible than other strains, and (aim 2) whether clustering of unvaccinated individuals explains why unexpectedly large measles outbreaks occur. Proposed techniques include branching process theory, which can be used to provide direct estimates of the extent of control, and causal inference to aid in covariate selection. Both maximum likelihood and simulation techniques will be used, along with mixed-effects modeling and parametric bootstrapping. If some strains are more transmissible or if clustering of unvaccinated individuals affects outbreak size, contact investigation strategies could be modified for greater efficiency. In addition, the results could be used to inform vaccination policy nationally. The proposed training plan includes hands-on research experience to execute the proposed aims and fulfill the applicant's dissertation requirement. Training will also include advanced coursework at UCSF and University of California, Berkeley and directed readings with the sponsor (Professor Travis Porco) and co-sponsor (Professor Wayne Enanoria). Additional training and mentorship will come from Dr. Jennifer Zipprich, Epidemiologist at the California Department of Public Health, Immunization Branch, and dissertation committee members, Professor Maria Glymour (UCSF) and Professor Jamie Lloyd-Smith (UCLA).