Medical Research Council Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London W2 1PG, United Kingdom.
Centre for Health Informatics Computing and Statistics, Lancaster Medical School, Lancaster University, Lancaster LA1 4YW, United Kingdom.
Proc Natl Acad Sci U S A. 2020 Sep 22;117(38):23636-23642. doi: 10.1073/pnas.1910181117. Epub 2020 Sep 8.
Some directly transmitted human pathogens, such as influenza and measles, generate sustained exponential growth in incidence and have a high peak incidence consistent with the rapid depletion of susceptible individuals. Many do not. While a prolonged exponential phase typically arises in traditional disease-dynamic models, current quantitative descriptions of nonstandard epidemic profiles are either abstract, phenomenological, or rely on highly skewed offspring distributions in network models. Here, we create large socio-spatial networks to represent contact behavior using human population-density data, a previously developed fitting algorithm, and gravity-like mobility kernels. We define a basic reproductive number [Formula: see text] for this system, analogous to that used for compartmental models. Controlling for [Formula: see text], we then explore networks with a household-workplace structure in which between-household contacts can be formed with varying degrees of spatial correlation, determined by a single parameter from the gravity-like kernel. By varying this single parameter and simulating epidemic spread, we are able to identify how more frequent local movement can lead to strong spatial correlation and, thus, induce subexponential outbreak dynamics with lower, later epidemic peaks. Also, the ratio of peak height to final size was much smaller when movement was highly spatially correlated. We investigate the topological properties of our networks via a generalized clustering coefficient that extends beyond immediate neighborhoods, identifying very strong correlations between fourth-order clustering and nonstandard epidemic dynamics. Our results motivate the observation of both incidence and socio-spatial human behavior during epidemics that exhibit nonstandard incidence patterns.
有些直接传播的人类病原体,如流感和麻疹,其发病率会持续呈指数级增长,且高峰期的发病率与易感个体的快速消耗相一致。但也有很多情况并非如此。虽然在传统的疾病动力学模型中,通常会出现一个持续的指数增长阶段,但目前对非标准流行模式的定量描述要么是抽象的、现象学的,要么依赖于网络模型中高度偏态的后代分布。在这里,我们使用人群密度数据、先前开发的拟合算法和类似引力的移动核创建了大型的社会空间网络,以表示接触行为。我们为这个系统定义了一个基本繁殖数 [Formula: see text],类似于用于隔间模型的繁殖数。在控制 [Formula: see text] 的情况下,我们探索了具有家庭-工作场所结构的网络,在这种网络中,不同程度的空间相关性可以通过来自类似引力的核的单个参数来形成家庭间接触。通过改变这个单一参数并模拟传染病的传播,我们能够确定更频繁的局部移动如何导致强烈的空间相关性,从而诱导出具有较低、较晚的流行高峰期的次指数爆发动力学。此外,当运动具有高度空间相关性时,峰值高度与最终规模的比值要小得多。我们通过扩展到直接邻居之外的广义聚类系数来研究网络的拓扑性质,确定了第四阶聚类与非标准流行动力学之间非常强的相关性。我们的结果促使人们在表现出非标准发病模式的传染病期间观察发病率和社会空间人类行为。