A novel modeling and analysis of fractional-order COVID-19 pandemic having a vaccination strategy

Abstract
Recently, many illustrative studies have been performed on the mathematical modeling and analysis of COVID-19. Due to the uncertainty in the process of vaccination and its efficiency on the disease, there have not been taken enough studies into account yet. In this context, a mathematical model is developed to reveal the effects of vaccine treatment, which has been developed recently by several companies, on COVID-19 in.this study. In the suggested model, as well as the vaccinated individuals, a five-dimensional ordinary differential equation system including the susceptible, infected, exposed and recovered population is constructed. This mentioned system is considered in the fractional order to investigate and point out more detailed analysis in the disease and its future prediction. Moreover, besides the positivity, existence and uniqueness of the solution, biologically feasible region are provided. The basic reproduction number, known as expected secondary infection which means that expected infection among the susceptible populations caused by this infection, is computed. In the numerical simulations, the parameter values taken from the literature and estimated are used to perform the solutions of the proposed model. In the numerical simulations, Adams-Bashforth algorithm which is a well-known numerical scheme is used to obtain the results.