Figure~(a) shows the result of a numerical simulation where $R_0=2.5$ (probably a low estimate for COVID-19), $\gamma = 1.1$, $\delta =0.00278$, and an initial condition where 0.0001\% of the population is infected. The peak of infections occurs after 83 days, with 23.6\% of the population being simultaneously infected. When the disease disappears, about 89\% of the population is infected.