Approximate Solutions of the RSIR Model of COVID-19 Pandemic

The Reduced SIR (RSIR) model of COVID-19 pandemic based on a two-parameter nonlinear first-order ordinary differential equation with retarded time argument is developed. An algorithm aimed to forecast the COVID-19 pandemic development by approximate solution of RSIR model is proposed. The input data for this algorithm are the cumulative numbers of infected people on three dates (e.g., today, a week ago, and two weeks ago).