Evolutionary dynamics analysis of virulence in viral infectious disease co-infection model

In this paper, we study transmission dynamics of viral infectious diseases co-infection model and evolution dynamics of different strains virulence. Firstly, we develop original strain transmission model by considering immune loss and reinfection mechanisms, and obtain stability of equilibrium in the model. When basic reproduction number R 01 > 1, we introduce a mutant strain at endemic equilibrium of original strain transmission model, and establish two strains co-infection model. Secondly, using invasion analysis method, we obtain properties of evolutionarily singular strategy through fitness function and evolutionary dynamics of average virulence and average transmission rate using population genetic method. Finally, numerical simulations are performed with COVID-19 data in the United States to obtain transmission rate as a function of virulence, contour plots of fitness function and time series diagrams of average virulence and average transmission rate, which provide theoretical guidance for controlling development of COVID-19 outbreaks.