Mathematical model of COVID-19 pandemic based on a retarded differential equation

A mathematical model of COVID-19 pandemic based on a two-parameter nonlinear first-order ordinary differential equation with retarded time argument is proposed. The model uses two parameters: the time of possible dissemination of infection by an individual virus carrier and the probability of contamination of a healthy population member in a contact with an infected one per unit time. The parameters can be given functions of time, which is particularly important in describing multi-peak pandemic. The model is applicable to any community (country, city, etc.) and provides an optimal balance between the adequate description of a pandemic inherent in the known SIR model and the relative simplicity for practical estimates. Examples of the model application are in qualitative agreement with the dynamics of COVID-19 pandemic.