“…The international scientific interest on Covid-19 is of great proportions, as indicated by the large number of publications in specialized journals of medicine, biology, mathematics, physics and chemistry, mainly (e.g. [5] , [6] , [10] , [11] , [12] , [13] , [20] , [22] , [24] , [29] , [31] ). The epidemic risk of each region is a function of factors such as geographic proximity, the population spatial distribution [32] , the economic development [3] and the migration index.…”