WSEAS Transactions on Computers
Print ISSN: 1109-2750, E-ISSN: 2224-2872
Volume 19, 2020
Effects of the Reproduction Number in a Seiird Model Describing the Time Evolution of COVID-19 at Count Ry Level
Author:
Abstract: We consider a compartmental model of SEIIRDtype which describes the time evolution of theCOVID-19 epidemy at the level of a country. For the reproduction number R(t), the crucial parameter whichinfluences the number of new cases, we consider an explicit form as a combination of trigonometric, exponentialand 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 rapidreduction below 1 due to a first lockdown which can have different intensities. The second phase consists of arelaxation of the restrictions having as a consequence an increase of the reproduction number within a rangeover 1. The numerical simulations show that in this case, after a period of some months with a low level of dailycases, the occurrence of a second wave is unavoidable, being inherent to the nature of the model. The intensityof the second wave depends on how much and how long the reproduction number R(t) has been over thethreshold value of 1, but also on the intensity of the first lockdown. All simulations show that the behaviour ofthe model is very sensitive with respect to the reproduction number. Small changes in its values may have asignificant impact on the long-term evolution of the epidemy at the country-level.
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Pages: 292-297
DOI: 10.37394/23205.2020.19.35