“…Following the lead of other investigators [4,33,[36][37][38], we adopt a discrete-time approach. In our SIR epidemic model, the time axis is marked off in equally spaced intervals 𝑡 = 0,1, … , 𝑇, where the duration of each interval is sufficiently small as to adequately approximate the classical, continuous-time version [5,[47][48][49][50].…”