ABSTRACT
In this article, the authors introduce a mathematical model of the critical Coronavirus Disease (Covid-19) situation in Thailand during March 2021 to August 2021. The work is divided into three parts. Firstly, the model is formulated with a description of the parameters defined in the model, the we compute the basic reproduction number (R0) and study the locally asymptotically stability of its disease free equilibrium point, the existence of endemic equilibrium point, and locally and globally asymptotically stability of its endemic equilibrium point. Secondly, we present a strategy using fixed point iterative methods for solving a nonlinear dynamical problem in form of Green's function for analysis of the parameters, the existence and convergence theorems of solutions are shown by the fixed point theorem techniques. Finally, the authors show the numerical to predict the future situation of coron-avirus disease in Thailand contain R0 and give the conclusion of this work. © 2022, Thammasat University. All rights reserved.