Before revision:  We started from a simple Susceptible, Infected, Recovered (SIR) model and we added the condition that, after a certain time, thebasic reproduction numberR0exponentially decays in time, as empirically suggestedby world data.
After revision:  We started from a simple Susceptible, Infected, Recovered (SIR) model and we added the condition that, after a certain time, the basic reproduction number R_0 exponentially decays in time, as empirically suggestedby world data.