Agent-based model and GLEaM. Top: The agent-based model is a stochastic and spatially-explicit simulation model where the agents represent individuals. The basic spatial structures considered in the model are the municipalities. The force of infection in the general population is assumed to decrease with the geographic distance among municipalities. The dependence on the distance is modeled by a gravity model as derived by the analysis of data on travel to school or work (grouped by all hierarchical administrative levels, from the national level down to the municipality level). The inset shows the explicit representation of individuals in the model enabling the simulations of the most important contacts for diseases transmission, i.e. household, school, and workplace contacts. The spatial spread of the epidemic is determined by i) transmission in the general population at the national scale and ii) transmission in schools and workplaces at a more local scale. Bottom: GLEaM, GLobal Epidemic and Mobility model. The world surface is represented in a grid-like partition where each cell — corresponding to a population value — is assigned to the closest airport. Geographic census areas emerge that constitute the subpopulations of the metapopulation model. The demographic layer is coupled with two mobility layers, the short-range commuting layer and the long-range air travel layer.