Incidence and population immunity to influenza and ARVI in the context of the COVID-19 pandemic

Abstract

The pandemic of the new COVID-19 infection has had an impact on the epidemic process of most known infectious diseases. Given the high pandemic potential and the economic damage caused by influenza and SARS, the assessment of the prevalence of these infections in modern realities seems relevant. Aim: to assess the current manifestations of the epidemic process of SARS and influenza during the COVID-19 pandemic. Official statistics data were used to study the manifestations of epidemic processes of influenza and SARS. For serological examination, blood serum samples from conditionally healthy adults (N=270) collected in February 2022 were used. The titer of IgG antibodies to strains of influenza virus H1N1 pnm09, influenza H3N2, influenza B (Phuket), influenza B (Washington) was determined using a hemagglutination inhibition reaction. The samples were examined by enzyme immunoassay for the presence of IgG antibodies to adenovirus, respiratory syncytial (RS) virus, metapneumovirus, rhinovirus and parainfluenza viruses of types 1 and 3. Against the background of the development of the COVID-19 pandemic, an increase in the incidence of influenza has been established to a maximum value in 2021 (65.99 per 100 thousand population). The prevalence of influenza in the capital was 4.6 times higher than the average in Russia (14.96 per 100 thousand population). A significant proportion of persons immune to the influenza virus (more than 60 %) with a maximum value for the influenza B virus was identified, which is consistent with the data on the prevalence of this variant of the pathogen in the etiological interpretation of the incidence in 2021. Among the pathogens of ARVI, the maximum proportion of seropositive was detected to rhinovirus (77.8 %), which corresponds to the data on the greatest prevalence of this pathogen in the etiological structure of this group of infections. The active circulation of the influenza virus and the vaccination of the population became the basis for the formation of a high level of population immunity to the corresponding virus, which was shown by the results of the assessment of the prevalence of specific IgG antibodies.