© 2020 Elsevier Ltd The pandemic of SARS-CoV-2 made many countries impose restrictions in order to control its dangerous effect on the citizens. These restrictions classify the population into the states of a flow network where people are coming and going according to pandemic evolution. A new dynamical model based on flow networks is proposed. The model fits well with the well-known SIR family model and add a new perspective of the evolution of the infected people among the states. This perspective allows to model different scenarios and illustrates the evolution and trends of the pandemic because it is based on the open data daily provided by the governments. To measure the severity of the pandemic along the time, a danger index (DI) is proposed in addition to the well-known R0 index. This index is a function of infected cases, number of deaths and recover cases while the transmission index R0 depends only on the infected cases. These two indexes are compared in relation to data from Spain and the Netherlands and additionally, it is shown the relation of the danger index with the policy applied by the governments.