Figure 1

(a) Population I(t) from the numerical solution of the SIR model in (1). (b) Reproduction Number \(R_t \) versus time. The lockdown phase is characterised by an exponential decrease in this parameter. The narrow, rectangle impulse at day 150 represents time-limited increase in the \(\beta \) coefficient, due to a large gathering event. Dot-dashed lines represent I(t) and \(R_t\) without any fluctuation, respectively in (a, b). Continuous lines represent the same quantities in the presence of fluctuations. \(\beta \) si affected by noise with correlation time \(\tau = 0\) days (blue), \(\tau = 30\) days (green), \(\tau = 100\) days (red). Here \(\sigma = 0.009\) and \(\langle \xi \rangle = 0\). The end of the lockdown phase is marked by the vertical dashed line.