FORMATION OF POPULATION IMMUNITY TO INFLUENZA VIRUSES IN PRE- AND POST-EPIDEMIC PERIODS IN LONG-TERM DYNAMICS AMONG THE POPULATION OF THE SVERDLOVSK REGION
Authors: Koltunov S.V. ,   The Center for Hygiene and Epidemiology in the Sverdlovsk Region, Russian Federation, Ekaterinburg, Romanov S.V. , Ponomareva A.V. , Korotkova I.A. , Bolgarova E.V. , Markaryan A.Yu. , Slobodenyuk A.V. , Grigorieva Y.V. , Malchikov I.A. ,   The Center for Hygiene and Epidemiology in the Sverdlovsk Region, Russian Federation, Ekaterinburg,   Directorate of the Federal Service for Supervision of Consumer Rights protection and Human Welfare in the Sverdlovsk Region, Russian Federation, Ekaterinburg,   Federal Budgetary Institution of Science "Federal Scientific Research Institute of Viral Infections "Virome" Federal Service for Surveillance on Consumer Rights Protection and Human Well-Being, Russian Federation, Ekaterinburg,   Federal Budgetary Institution of Science "Federal Scientific Research Institute of Viral Infections "Virome" Federal Service for Surveillance on Consumer Rights Protection and Human Well-Being, Russian Federation, Ekaterinburg,   Federal Budgetary Institution of Science "Federal Scientific Research Institute of Viral Infections "Virome" Federal Service for Surveillance on Consumer Rights Protection and Human Well-Being, Russian Federation, Ekaterinburg,   Federal State Budgetary Institution of Higher Professional Education «Urals State Medical University» of the Ministry of Healthcare of the Russian Federation, Russian Federation, Ekaterinburg,   Federal State Budgetary Institution of Higher Professional Education «Urals State Medical University» of the Ministry of Healthcare of the Russian Federation, Russian Federation, Ekaterinburg,   Federal Budgetary Institution of Science "Federal Scientific Research Institute of Viral Infections "Virome" Federal Service for Surveillance on Consumer Rights Protection and Human Well-Being, Russian Federation, Ekaterinburg; Federal State Budgetary Institution of Higher Professional Education «Urals State Medical University» of the Ministry of Healthcare of the Russian Federation, Russian Federation, Ekaterinburg
Published: July 2024

The aim of the work was to evaluate the formation of population immunity to influenza in the pre- and post-epidemic periods in the long-term dynamics among the population of the Sverdlovsk region. Results: he lowest number of seropositive individuals with protective antibody titers (1≥40) to influenza A(HlNl) virus - 36.4-49.1% on the eve of the epidemic seasons 2015-2016, 2019-2020, 2020-2021, 2021-2022 - was detected, to influenza A(H3N2) virus - 38.0-50.0% in 2016-2017, 2018-2019, to in-fluenza B virus - 40.4;45.1;34.5% in 2019-2020, 2020-2021, 2021-2022 respectively. At the end of the listed epidemic seasons, an increase in protective antibody titers was detected in accordance with the proportion of the above viruses. The exception was the seasons 2019-2020 and 2020-2021, when despite the minimum number of seropositive persons to influenza A(HlNl) virus, their number at the end of the season practically did not change (p>0.05), and PCR studies did not reveal the circulation of this virus in the population. This fact can be explained by the suppression of the mentioned virus circulating at this time by the epidemic variant of Wuhan strain SARS-CoV-2. Discussion: It is hypothesized that when the level of population immunity (PI) to influenza viruses was lowest before an epidemic upsurge caused by a particular influenza virus, the incidence rates of this virus in the population became higher when the epidemic occurred. Consequently, the immune layer of the population to circulating influenza viruses was in correlation with the activity of the epidemic process. Conclusion: the determination of the immune layer continues to be a tool for predicting the epidemic process in influenza. The conducted research proves its relevance.