Fig. 2.

Panel (a) shows the time paths for the time-varying reproduction number, $\tilde{R}$. Panel (b) contains the phase diagram that shows the evolution of the fraction of the actively infected population against the fraction of the susceptible population with and without reinfection. Panels (c)–(e) show the fraction of the actively infected population over time under the reinfection (solid) and no-reinfection (dashed) scenarios and with different speed of the change in $\tilde{R}$. Panels (c)–(e) differ in the size of the immunity waning ratio, ω.