  The aim of the paper is to describe two models of Covid-19 infection
dynamics. For this purpose a special class of branching processes with two
types of individuals is considered. These models are intended to use only the
observed daily statistics to estimate the main parameter of the infection and
to give a prediction of the mean value of the non-observed population of the
infected individuals. Similar problems are considered also in the case when the
processes admit an immigration component. This is a serious advantage in
comparison with other more complicated models where the officially reported
data are not sufficient for estimation of the model parameters. In this way the
specific development of the Covid-19 epidemics is considered also for all
countries as it is given in the specially created site
http://ir-statistics.net/covid-19 where the obtained results are updated daily.
