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.

Hepatitis B is an infectious disease that leads to severe health problems, with the risk of chronicity and death. The World Health Organization (WHO) has shown that about 4.5 million premature deaths from the infection could be prevented by 2030 in low- and middle-income countries through vaccination, diagnostic tests, drugs, and education campaigns. The main goal of the WHO global hepatitis strategy is to reduce new infections by 90 % and deaths by 65 % between 2016 and

2030. The successes of hepatitis B vaccine prophylaxis are the basis for setting the ambitious goal of eliminating the disease in the future. However, to date, many questions about the organization and planning of regional vaccination programs remain unresolved and provoke discussions among specialists around the world, including in Russia. In order to systematize and summarize the scientific literature on prevention, as well as to evaluate its effectiveness, we performed a literature search using the electronic bibliographic resources https://pubmed.ncbi.nlm.nih.gov/ and https://elibrary.ru/ using the key words «hepatitis B» and «vaccine prophylaxis». Analysis of scientific papers allowed us to characterize some manifestations of hepatitis B epidemic process and reveal its modern features in the territory of Russia, including risk groups. Aspects of genetic heterogeneity of HBsAg pathogen circulating in Russian territory as well as in adjoining states are given in details. The organization of vaccine prophylaxis is considered; the used immunobiological preparations are characterized. The results of the work define the role of serological studies in the system of epidemic surveillance for hepatitis B, as well as their significance for formation of adequate tactics of vaccination of the population, including in risk groups.