Fig. 1 Estimation of the number of COVID-19 cases in Wuhan, China (December 2019–February 2020, R0 = 1.9, 2.6, and 3.1). In all, 11,044, 70,258, and 227,989 represent the estimated number of COVID-19 cases by the end of February 2020 in Wuhan, China, with R0 = 1.9, 2.6, and 3.1, respectively.