In this brief report, a modified version of the well-known mathematical epidemic model SEIR is used to analyze the epidemics course of COVID-19 in six different countries. To this goal, the parameters of the SEIR model are identified by using publicly available data for the corresponding countries: France, Italy, Spain, Germany, Brazil and Russia. The identified model is then applied for the prediction of the SARS-CoV-2 virus propagation under different conditions of confinement. For this purpose, an interval predictor is designed allowing variations and uncertainties in the model parameters to be taken into account. The code and data are available in Github.