Fig. 3.

Infectious disease transmission at different transmission rate (β), recovery rates (γ) and average number of person-to-person contacts per day (n_p) under $R_0=1.8$. (a) $\beta ={\beta }_0$, $\gamma ={\gamma }_0$and $n_p=n_{p0}$. (b) $\beta =0.5{\beta }_0$, $\gamma =0.5{\gamma }_0$and $n_p=n_{p0}$. (c) $\beta =2{\beta }_0$, $\gamma =2{\gamma }_0$and $n_p=n_{p0}$. (d) $\beta ={\beta }_0$, $\gamma =0.5{\gamma }_0$and $n_p=0.5n_{p0}$. The red line depicts the source city and the black line depicts the downstream city; the x-axis shows the time (day); the y-axis shows the percentage of infected people; and the number on the right side of the figure is the value of $\Delta P_{c_s}^{c_d}$.

*β₀, γ₀ and n_p0 are the defaults (${\beta }_0=1.56\times {10}^{-3}$, ${\gamma }_0=4.17\times {10}^{-2}$ and $n_{p0}=400$, respectively). Detailed information is provided in Section 2.2.