Empirical space-time evaluation of priority groups for influenza control

描述（由申请人提供）：流感疫苗接种是预防工作的主要内容，最初针对老年人和并发症高风险人群。然而，儿童患流感的风险最大，其感染率平均高于任何其他年龄组，并已被确定为流感家庭传播的主要媒介。因此，除了直接使儿科人群受益外，儿童常规疫苗接种有可能大大减少人口传播。在2006- 2007年流感季节，普遍接种疫苗的建议将包括三岁和四岁儿童。这一疫苗政策转变为回答一个关键问题创造了条件：新疫苗推荐是否会降低儿科和成人年龄组的流感负担？除了年龄组的影响外，人口密度、贫困和家庭规模等人口层面的其他人口特征可能是流感传播的重要决定因素，因此是高度优先的目标。虽然有一些经验证据表明地理位置与流感在大范围内的关系，但令人惊讶的是，关于影响当地传播的因素的经验信息很少。记录流感流行的经验空间格局是了解驱动流行病波动的潜在机制的第一步。本研究的总体目标是利用来自国家和地方监测数据的经验证据来评估流感控制和预防的高价值目标。在地方和国家层面上，控制跨空间和时间疾病模式的潜在因素将被建模，以回答两个关键问题：(1)新的建议是否会降低目标年龄组（3-4岁）的发病率以及整个人口的总体发病率和死亡率？(2)是否存在其他高危人群，根据他们对病毒的易感性和传播能力，可以成为监测和控制的重要目标？目标1将依靠自然实验来经验性地评估学龄前儿童接种疫苗的作用。目标2将涉及探索性工作，以模拟流感的地方地理传播，并确定影响疾病传播时间和程度的重要人口普查水平协变量。拟议的研究利用独特的监测数据集来评估当前政策，并解决可能对其进行扩展的问题。对于每个目标，横断面时间分析将在两个尺度上进行：全州和全国。该项目将利用丰富而独特的数据来源，包括儿科住院、急诊和死亡率，所有这些数据都是前瞻性收集的。统计模型将以这些历史数据为基础，以确定新政策是否会影响观察到的传播模式人群（目标1），以及针对其他高危人群是否会进一步减少社区疾病（目标2）。这项研究的结果将使决策者能够制定有关大流行间和大流行流感的资源分配和疫苗接种战略的卫生政策。本研究的总体目标是利用来自国家和地方监测数据的经验证据来评估流感控制和预防的高价值目标人群。拟议研究的结果将使决策者能够制定有关流行病和大流行性流感的资源分配和最佳疫苗接种战略的卫生政策。特别是，这项研究将评估疾病控制和预防中心免疫实践咨询委员会关于给三、四岁儿童接种疫苗的建议是否会降低整个人群的流感负担，以及新政策是否也应该关注其他高危人群。

DESCRIPTION (provided by applicant): Vaccination against influenza is the mainstay of prevention efforts and was initially targeted at older individuals and those with high risk of complications. However, children are at the greatest risk of illness from influenza with infection rates averaging higher than any other age group and have been identified as predominant vectors in the household spread of influenza. Therefore, besides directly benefiting the pediatric population, the routine vaccination of children has potential to substantially reduce population-wide transmission. For 2006- 2007 influenza season, universal vaccination recommendations will include three and four year olds. This vaccine policy shift creates conditions to answer a critical question: will the new vaccine recommendation result in a lower burden of influenza across both pediatric and adult age groups? Beyond the effect of age group, other population-level demographic characteristics such as population density, poverty and household size may be important determinants of influenza spread and thus high priority targets. Although there is some empirical evidence on the relationship between geography and influenza across large scales, there is surprisingly little empirical information on the factors that influence local spread. Documenting empirical spatial patterns of influenza epidemics represents a first step toward understanding underlying mechanisms that drive epidemic fluctuations. The overall goal of this research is to use empirical evidence from both national and local surveillance data to evaluate high value targets for influenza control and prevention. The underlying factors controlling patterns of illness across space and time, on both local and national levels will be modeled to answer two critical questions: (1) Will the new recommendations reduce morbidity in the targeted age group (3-4 years) as well as overall morbidity and mortality across the population? (2) Are there other at-risk populations that would make important targets for surveillance and control based on their susceptibility and capacity to spread to virus? Aim 1 will rely on a natural experiment to empirically assess the role of vaccination of preschoolers. Aim 2 will involve exploratory work to model local geographic spread of influenza and identify important census-level covariates that influence the timing and magnitude of disease transmission. The proposed study leverages unique surveillance datasets to evaluate the current policy as well as to address possible extensions to it. For each aim, cross-sectional time analysis will be performed at two scales: state- wide, and national. The project will exploit rich and unique data sources including, pediatric hospitalizations, emergency visits and mortality, all collected prospectively. Statistical models will be based on these historical data to determine whether new policy influences the observed transmission patterns population (Aim 1), and whether targeting other at-risk populations would provide additional reduction of community-wide illness (Aim 2). The findings of this study will allow decision makers to formulate health policy regarding resource allocation and vaccination strategies for both inter-pandemic and pandemic influenza. The overall goal of this research is to use empirical evidence from both national and local surveillance data to evaluate high value target populations for influenza control and prevention. The findings of the proposed study will allow decision makers to formulate health policy regarding resource allocation and optimal vaccination strategies for both epidemic and pandemic influenza. In particular, the study will evaluate whether a recommendation by the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices to vaccinate three and four year olds will result in a lower burden of population-wide influenza burden and whether new policy should also focus on other at-risk populations.