  This manuscript proposes a model of $n$ distinct populations interaction
structured SEIR to describe the spread of COVID-19 pandemic diseases. The
proposed model has the flexibility to include geographically separated
communities as well as taking into account aging population groups and their
interactions. We show that distinct assumptions on the dynamics of the proposed
model lead to a plateau-like curve of the infected population, reflecting
collected data from large countries like Brazil. Such observations aim to the
following conjecture: " Covid-19 diseased diffusion from the capitals to the
Brazil interior, as reflected by the proposed model, is responsible for
plateau-like reported cases in the country". We present numerical simulations
of some scenarios and comparison with reported data from Brazil that
corroborate with the aforementioned conclusions.
