描述Ry计数水平下COVID-19时间演化的第三模型中繁殖数的影响

Flavius Guias
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引用次数: 1

摘要

我们考虑了一个seiird型的区隔模型,该模型描述了COVID-19流行病在国家层面的时间演变。对于影响新情况数量的关键参数再现数R(t),我们考虑了三角函数、指数函数和高斯函数组合的显式形式。可以调整各个部分的系数,以使R(t)的轮廓匹配不同的场景。它们的共同结构说明了在大多数国家观察到的真实行为。最初,我们可以观察到较大的R(t)值,这导致了流行病的第一波爆发,随后由于第一次封锁的强度不同,R(t)值迅速降至1以下。第二阶段包括放宽限制,结果使繁殖数量在1以上的范围内增加。数值模拟表明,在这种情况下,经过几个月的低水平日病例后,第二波的发生是不可避免的,这是模型固有的性质。第二波疫情的强度取决于繁殖数R(t)超过阈值1的程度和持续时间,但也取决于第一次封锁的强度。仿真结果表明,该模型的行为对繁殖数非常敏感。其价值的微小变化可能对国家一级流行病的长期演变产生重大影响。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
Effects of the Reproduction Number in a Seiird Model Describing the Time Evolution of COVID-19 at Count Ry Level
We consider a compartmental model of SEIIRDtype which describes the time evolution of the COVID-19 epidemy at the level of a country. For the reproduction number R(t), the crucial parameter which influences the number of new cases, we consider an explicit form as a combination of trigonometric, exponential and gaussian functions. The coefficients of the individual parts can be adapted in order that the profile of R(t) matches different scenarios. Their common structure illustrates the real behaviour observed in most countries. Initially we can observe large values of R(t) which enforce the first wave of the epidemy, followed by a rapid reduction below 1 due to a first lockdown which can have different intensities. The second phase consists of a relaxation of the restrictions having as a consequence an increase of the reproduction number within a range over 1. The numerical simulations show that in this case, after a period of some months with a low level of daily cases, the occurrence of a second wave is unavoidable, being inherent to the nature of the model. The intensity of the second wave depends on how much and how long the reproduction number R(t) has been over the threshold value of 1, but also on the intensity of the first lockdown. All simulations show that the behaviour of the model is very sensitive with respect to the reproduction number. Small changes in its values may have a significant impact on the long-term evolution of the epidemy at the country-level.
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