Fig. 2

Demographic and epidemic dynamics of Flight-SEIR. The figure shows the movements of exposed individuals \(E_{i}^{in}\) and \(E_{i}^{out}\) between the populations. Each population \(C_i\) maintains its own epidemic states \(S_i\), \(E_i\), \(I_i\), and \(R_i\). An exposed individual can either come from other populations or be infected by an infectious individual within the same population. More details on the notations can be found in Table 1