自新冠肺炎扩散开始以来，关于流行病模型的研究数量急剧增加。对于决策者来说，了解疾病将如何传播，以及政策和环境对传播的影响是很重要的。在本文中，我们对标准传染病模型提出了两个扩展:(1)我们考虑根据当前感染的严重程度采取的预防措施，这些措施是适应性的，并随着时间的推移而变化。考虑到多个城市和地区，以及这些城市/地区之间的人口流动，同时考虑到每个地区可能有不同的预防措施。虽然在大流行期间经常观察到适应性措施和人口流动性，但这些影响很少在经典的流行病模型中明确建模和研究。我们提出的模型导致了一个平稳现象:感染这种疾病的人数在很长一段时间内保持在同一水平。我们展示了需要满足什么条件才能使传播呈现出平台期，我们展示了这种现象是相互依赖的:当考虑多个城市时，条件不同于单个城市。我们从真实世界的数据中证实，在当前的新冠肺炎发展中，高原现象确实存在于世界许多地区。最后，我们对单城市模型的高原现象进行了理论分析，得出了一系列关于高原产生和结束以及高原高度和长度的结果。我们的理论结果与我们的实验结果吻合得很好。

原文题目：COVID-19 Plateau: A Phenomenon Of Epidemic Development Under Adaptive Prevention Strategies

原文：Since the beginning of the COVID-19 spreading, the number of studies on the epidemic models increased dramatically. It is important for policy makers to know how the disease will spread, and what are the effects of the policies and environment on the spreading. In this paper, we propose two extensions to the standard infectious disease models: (a) We consider the prevention measures adopted based on the current severity of the infection, those measures are adaptive and change over

time. (b) Multiple cities and regions are considered, with population movements between those cities/regions, while taking into account that each region may have different prevention measures. While the adaptive measures and mobility of the population were often observed during the pandemic, these effects are rarely explicitly modeled and studied in the classical epidemic models. The model we propose gives rise to a plateau phenomenon: the number of people infected by the disease stay at the same level during an extended period of time. We show what are conditions needs to be met in order for the spreading to exhibit a plateau period, and we show that this phenomenon is interdependent: when considering multiples cities, the conditions are different from a single city. We verify from the real-world data that plateau phenomenon does exists in many regions of the world in the current COVID-19 development. Finally, we provide theoretical analysis on the plateau phenomenon for the single-city model, and derive a series of results on the emergence and ending of the plateau, and on the height and length of the plateau. Our theoretical results match well with our empirical fifindings.

原文作者：Ziqiang Wu，Hao Liao ，Alexandre Vidmer ，Mingyang Zhou，Wei Chen

原文链接：https://arxiv.org/pdf/2011.03376.pdf