Heterogeneity of the modified SIR-model parameters of waves of COVID-19 epidemic process in the Russian Federation

Introduction. The work is dedicated to the parameterization of the COVID-19 epidemic process, taking into account the specifics of the Russian Federation regions. Purpose of study is the analysis of the spatio-temporal distribution of heterogeneous indicators of the spread of COVID-19 based on the formalization and parametrization of waves of the epidemic process, bearing in mind regional specifics. Materials and methods. SIR (+L) model as a modification of the classic SIR model, reflecting the trend in the transition of the susceptible to the action of the virus (S – susceptible) population to the group of infected (I – infected), recovered (R – recovered) and the dead (L – letal) was used as a basic model of the epidemic process. Results. Time ranges of activation of the epidemic process in the regions of the Russian Federation, corresponding to waves of domination of certain strains of the virus, have been allocated on the basis of the analysis of time series COVID-19 morbidity with a week period of averaging. In total, starting from September 6, 2020 and ending on February 25, 2023, four epidemic waves have been allocated for each region. Analysis of SIR (+L) model parameters for each wave by regions of the Russian Federation made it possible to establish a number of characteristic trends and obtain interpretable directions of influence on the epidemic process individual stages, with the subsequent development of systemic strategic decisions on the preservation of population health and its level of safety at the regional and country-wide scale. Limitations. The presented modification of the SIR model (SIR (+L) model) is a significant simplification of the real epidemic process and does not allow describing a number of observed effects. Conclusion. Based on the results of the parametrization of the epidemic process, the main features and patterns of the spread of the COVID-19, the intensity of recovery and mortality were established. A further direction of research may be the complication of the epidemic process model, the addition of new parameters to it, taking into account the division of the population into gender and age groups, diseases by severity, grouping according to the territorial and social principle, and the identification of the latent morbidity.