论文标题
2019年新颖冠状病毒流行期间的分段二次增长
Piecewise quadratic growth during the 2019 novel coronavirus epidemic
论文作者
论文摘要
COVID-19-19的流行病的时间增长的时间增长是次指数的。在这里，我们表明，一项分段二次法律在2020年3月底的1月20日及以后的前三个死亡人数的三十天内提供了极好的拟合度。还有一个简短的指数增长中期。在第二个二次生长阶段，生长的特征时间约为一开始的八倍，这可以理解为单独的热点的发生。当进一步扩散仅发生在感染区域的郊区时，二次行为可以由外围生长动机。我们还研究了一个简单的流行病模型的数值解，其中考虑了系统的空间扩展。为了模拟中国以外的延迟发作与中国早期在一个模型中的假设最少的模型，我们采用了几个热点的初始条件，其中一个人的饱和度比其他几个热点早得多。在每个部位，二次增长开始时，当局部感染达到一定的饱和水平时。然后，死亡的总数确实确实遵循了分段二次行为。
The temporal growth in the number of deaths in the COVID-19 epidemic is subexponential. Here we show that a piecewise quadratic law provides an excellent fit during the thirty days after the first three fatalities on January 20 and later since the end of March 2020. There is also a brief intermediate period of exponential growth. During the second quadratic growth phase, the characteristic time of the growth is about eight times shorter than in the beginning, which can be understood as the occurrence of separate hotspots. Quadratic behavior can be motivated by peripheral growth when further spreading occurs only on the outskirts of an infected region. We also study numerical solutions of a simple epidemic model, where the spatial extend of the system is taken into account. To model the delayed onset outside China together with the early one in China within a single model with minimal assumptions, we adopt an initial condition of several hotspots, of which one reaches saturation much earlier than the others. At each site, quadratic growth commences when the local number of infections has reached a certain saturation level. The total number of deaths does then indeed follow a piecewise quadratic behavior.
