Fig. 2.

Simulation of a deterministic SIR model for a population of 10⁶ individuals. The infection rate parameter is periodically modulated $({\beta }_0=0.3\times {10}^{-6},$$A=0.2\times {10}^{-6}),$ with $\gamma =0.12$ and $\omega =2\pi /10$. This corresponds to variations of the basic reproduction number R₀ ∈ [0.8, 4.16] with a period of 10 days.