Fig. 1.

SIR model. a) Infection spread scenario. At the initial condition, the total population is composed of a percentage of infected individuals (red) and the remaining one of susceptible individuals (blue). Upon exposure, a percentage of susceptible became infected, with an initial probability $\beta$ = 0.5; then, a percentage of infected die or recover and then became removed (green), with an initial probability $\gamma$ = 0.5. Infected individuals can still spread the infection, while removed individuals are no longer susceptible to infection. b) Model flow diagram. Upon exposure, individuals progress from susceptible (S) to infected (I) with a contact rate$\beta$. Then, infected individuals that die or recover will be removed (R) with a recovery rate $\gamma$.