Real-world validation of fractional-order model for COVID-19 vaccination impact

In this manuscript, we develop a fractional-order mathematical model to characterize the propagation dynamics of COVID-19 outbreaks and assess the influence of vaccination interventions. The model comprises a set of eight nonlinear fractional-order differential equations in the Caputo sense. To establish the existence and uniqueness of solutions, we employ the fixed-point technique. Furthermore, we employ the effective fractional Adams-Bashforth numerical scheme to explore both the approximate solutions and the dynamic behavior inherent to the examined model. All of the results are numerically visualized through the consideration of various fractional orders. Furthermore, the real data from three different countries are compared with the simulated results, and good agreements are obtained, revealing the effectiveness of this work.