Fig. 2.

The change of epidemic features with time for different ${\alpha }^{\prime }s$. The fitting epidemic curve $C_I(t)$, the number of individuals in the L state L(t) and in the A state A(t) versus time (unit: day) with the estimated parameters a $\beta =0.305$, $\lambda =0.16$ when $\alpha =0$, b $\beta =0.302$, $\lambda =0.15$ when $\alpha =0.05$, c $\beta =0.307$, $\lambda =0.22$ when $\alpha =0.1$, d $\beta =0.3$, $\lambda =0.17$ when $\alpha =0.2$. The data is the cumulative number of confirmed cases of Wuhan. The values of other parameters are set to: ${\gamma }_1=\frac{1}{21}$, ${\gamma }_2=\frac{1}{10}$, ${\gamma }_3=\frac{1}{15}$, $\delta =0.03$, $l=0.0083$ before January 23, 2020, and $l=0$ later