In all, 81,393 represents the estimated peak number of COVID-19 cases on 19 February 2020 in Wuhan, China with R0 = 0.5; 84,520 represents the estimated peak number of COVID-19 cases on 23 February 2020 in Wuhan, China with R0 = 0.9; E: number of exposed cases; I: number of infectious cases; E was assumed to be 30 times of I at baseline.