Features of the epidemic process in the spread of a new coronavirus infection COVID-19 on the territory of the metropolitan area in the period 2020–2022

Abstract

Introduction Conducting a comprehensive epidemiological etiological analysis of the development of the СОVID-19 pandemic in a metropolitan area is of interest to specialists of didderent profiles (epidemiologists, infectious disease specialists, pediatricians, therapists, immunologists, virologists). An important element of epidemiological surveillance is the assessment of collective immunity to infectious agents, including the SARS-CoV-2 virus. The natural ability of viruses to variability leads to the emergence of new types and strains. Currently, a number of mutations and polymorphisms have been identified that affect the structure and stability of proteins, factors of susceptibility to SARS-CoV-2 infection, pathogenicity and virulence of the virus, and the ability to “elude” the immune response of the host organism.The aim of the work was to assess evaluate the character of the epidemic process development of a new coronavirus infection on the territory of the metropolitan area in the period 2020–2022.Materials and methods A total of 331,013 people were examined by PCR for the presence of SARS-CoV-2 RNA in nasopharyngeal and oropharyngeal swabs. Specific IgM and IgG antibodies to SARS-CoV-2 in serum were detected by ELISA in 42,955 people. Genetic variants of the virus were typed (by PCR and sequencing).Results During the entire follow-up period, the highest percentage of “positive for Covid-19” was observed in February 2022 (58.9 %) and September 2022 (46.8 %). Among the total number of patients examined (n = 331,013), adult patients accounted for the largest proportion, – 83.9 %, children – 16.1 %. The proportion of individuals with specific IgG to SARSCoV-2 in 2020–2021 ranged from 53.3–82.6 %.Discussion In 2020–2022, there was an increase in the proportion of individuals with detectable RNA virus. The greatest infection was observed in the age groups 19–27 years and 28–65 years. It was found that the linear dependence of the increase in the specific weight of seropositive persons with respect to IgG among the residents of Ekaterinburg has a progressive trend, the approximation reliability coefficient R2 corresponds to 0.8172. In samples of patients examined in April–August 2022, markers of the genetic variant Omicron were detected in 96.9 % of cases. The increase in the structure of infected pediatric population (almost twofold over 2020–2022 years) is probably caused by the adaptation of the pathogen to a new susceptible cohort of people.Conclusion The dynamics of the number of people examined and the proprtion of detectability of SARS-CoV-2 RNA in Ekaterinburg during the entire period of the pandemic (March 2020–December 2022) had a wave-like character. By the end of 2022, the level of seropositive individuals in all age groups increased significantly, which confirms the presence of collective immunity in the territory.