  The phenomenological mathematical model of COVID-19 spreading is proposed for
large countries with geographical differentiation of population density.
According to the model COVID-19 spreading takes the form of several
spatio-temporal waves developing almost independently and simultaneously in
areas with different population density. The intensity of each wave is
described by a power-law dependence. The parameters of dependence are
determined by real statistical data at the initial stage of the disease spread.
The results of the model simulation were verified using statistical data for
the Republic of Belarus. Based on the developed model, a forecast calculation
was made at the end of May, 2020. The accuracy of forecasting the total number
of cases for a period of 3 months in the proposed approach was about 3 percent.
