A delayed dynamical model for COVID-19 therapy with defective interfering particles and artificial antibodies.

In this paper, we use delay differential equations to propose a mathematical model for COVID-19 therapy with both defective interfering particles and artificial antibodies. For this model, the basic reproduction number [Math Processing Error] R 0 is given and its threshold properties are discussed. When [Math Processing Error] R 0 < 1 , the disease-free equilibrium [Math Processing Error] E 0 is globally asymptotically stable. When [Math Processing Error] R 0 > 1 , [Math Processing Error] E 0 becomes unstable and the infectious equilibrium without defective interfering particles [Math Processing Error] E 1 comes into existence. There exists a positive constant [Math Processing Error] R 1 such that [Math Processing Error] E 1 is globally asymptotically stable when [Math Processing Error] R 1 < 1 < R 0. Further, when [Math Processing Error] R 1 > 1 , [Math Processing Error] E 1 loses its stability and infectious equilibrium with defective interfering particles [Math Processing Error] E 2 occurs. There exists a constant [Math Processing Error] R 2 such that [Math Processing Error] E 2 is asymptotically stable without time delay if [Math Processing Error] 1 < R 1 < R 0 < R 2 and it loses its stability via Hopf bifurcation as the time delay increases. Numerical simulation is also presented to demonstrate the applicability of the theoretical predictions. [ABSTRACT FROM AUTHOR]