Marina I. Korabelnikova

Introduction. Genetic monitoring of hepatitis A virus (HAV) is an important tool for surveillance of this infection and the identification of hepatitis A outbreaks. The aim of the study was to analyze the genetic diversity of HAV variants involved in sporadic and cluster cases of hepatitis A in 2022–2025. Materials and methods. A total of 402 HAV VP1/2A partial sequences isolated from sporadic and cluster cases in 2022–2025 in various regions of the Russian Federation were analyzed. Phylogenetic trees were constructed using a Bayesian approach implemented in the Beast2 software package using HAV sequences isolated in regions of the Russian Federation and neighboring countries since 1998. To assess changes in genetic diversity, p-distance values were analyzed in four HAV sequence samples, divided based on virus genotype and the year the sequences were isolated — before or after 2020. Results. The persistent circulation of two HAV genotypes, IA and IIIA, was demonstrated. The share of genotype IA was 78.4%, genotype IIIA — 12.7%, and imported genotype IB — 8.9%. Both genotypes, IA and IIIA, contribute to both sporadic and outbreak cases. 98% of HAV genotype IA isolates belonged to a single lineage originating from the strain that caused the 2010 outbreak in Moscow. Analysis of p-distance values confirmed a decrease in HAV genetic diversity — for genotype IA before 2020, this indicator ranged from 0.000 to 0.316, and from 0.000 to 0.087 in 2020–2024. For genotype IIIA, a decrease in the p-distance indicator was also noted, from 0.000–0.080 before 2020 to 0.000–0.029 in 2020–2024. Conclusion. The obtained results indicate a decrease in the genetic diversity of HAV against the background of a decrease in hepatitis A incidence rates, and suggest that analysis of longer regions of the viral genome might be required for molecular surveillance and outbreak investigation in the future, if the trend of decreasing genetic diversity of the virus remain.

Introduction. A sharp increase in the registered incidence of chronic hepatitis C, exceeding the average country level by more than 3 times, was noted in Omsk Region since 2023. The objective of the study was to answer the question of whether the observed increase in incidence is a consequence of the recent sharp increase in cases of hepatitis C virus (HCV) transmission, using molecular genetic analysis. Materials and methods. Amplification of HCV core/E1 fragment and Bayesian phylogenetic analysis of corresponding nucleotide sequences were performed for serum samples from 344 patients with chronic hepatitis C diagnosed in 2022–2023, which accounted for 12.6% of all chronic hepatitis C cases diagnosed during this period in Omsk Region (n = 2730). Results. Phylogenetic analysis demonstrated the presence of regional HCV clusters formed in 1990–2000s (95% HPD 1980–2014). The majority (86.0%, 295 out of 343) of HCV genotype 1a, 1b, 2a, 2c, 2k and 3a sequences isolated in 2023–2024 belong to different lineages circulating in the region for at least 10 years, which, together with the absence of large, homogeneous clusters with a recent tMRCA suggests the absence of a recent epidemiological link between these HCV cases. However, 12 (3.5%) sequences formed pairs with divergence in 2021–2023 (95% HPD 2018–2024), which indicates recent infection and suggests the presence of an epidemiological link between these cases of infection. Such pairs were identified for HCV genotypes 1a, 1b, 2a and 3a. Conclusion. The observed upsurge in chronic hepatitis C incidence in Omsk Region apparently reflects the accumulated number of cases of HCV infection in the region resulted from transmissions occurred 10–20 or more years ago, and is a consequence of the increase in the HCV testing coverage. With an increase in the testing rates, especially in vulnerable groups where a significant number of undetected HCV infections are concentrated, an increase in the incidence of chronic hepatitis C can be expected in other regions of the country.

A serious problem on the way to creating population immunity is the anti-vaccination movement and medical diversions from immunization. The increase in the number of parental refusals to vaccinate is due to a number of reasons, one of which is the passive position of medical workers in promoting vaccination among the population, which is the result of insufficient awareness of this issue. In addition, the active activity of a mass and aggressive media campaign about the dangers of vaccinations also deals a blow to the creation of collective immunity. The purpose of the study: to identify the causes that affect the negative attitude of the population and medical workers to vaccination work and to evaluate measures aimed at an adequate attitude to vaccination. As part of the European Immunization Week, a survey of the population on immunoprophylaxis was conducted. It has been found that health workers are more committed to immunization for themselves and their children. At the same time, it is noted that persons with medical education can conduct subjective overdiagnosis, identifying unjustified contraindications to vaccination and signs of adverse reactions in themselves and their children. When comparing the causes of negative attitudes towards vaccination among medical workers and the population without medical education, it was revealed that for doctors the main causes are adverse reactions and post — vaccination complications that may appear after vaccination or have already been observed in the respondents. Thus, the conducted research made it possible to characterize the factors influencing the commitment of the Moscow population to immunoprophylaxis and identify priority areas for overcoming the formation of public opinion aimed at refusing preventive vaccinations.

Hepatitis B (HB) remains one of the serious medical and social health problems, and to assess the epidemiological situation, it is necessary to analyze the state of population immunity by collecting information on its intensity during serological studies. The aim of the work is to assess the level of population immunity against HB in the population of the Russian Federation in 2017 to 2022. Materials and methods. The results of serological monitoring for the presence of anti-HBs, provided by territorial laboratories of medical institutions of each subject of the Russian Federation in 2017 to 2022, were analyzed. The cohort of subjects in each subject of the Russian Federation consisted of persons in the age groups 3–4, 16–17, 20–29, 30–39, 40–49 years old, numbering at least 100 people each. The analysis of the obtained data for 6 years (2017–2022) was carried out using averaged data for every two years – 2017–2018, 2019–2020 and 2021–2022. The number of study cohorts during these time intervals was 88,151, 84,166 and 97,274 people, respectively. Results and discussion. The average values of the proportion of persons with immunity against HB were 69.0% in 2017–2018, 66.2% in 2019-2020 and 61.3% in 2021–2022. The highest proportion of people with protective immunity against hepatitis B was observed in the age group of 20-29 years. The proportion of children 3-4 years old who had anti-HBs detected at a concentration exceeding 10 IU/l was 65.8–72.5%, and 16–17 years old – 49.6–64.9%. The intensity of post-vaccination immunity against HB in children 16-17 years old should be considered insufficient. Conclusion. An analysis of serological studies results for the period from 2017 to 2022 showed that the potential of vaccine prevention of hepatitis B, carried out since 2006 within the framework of the priority National Project «Health», is not fully realized.

Introduction. Given the unfavorable epidemic situation with chickenpox and shingles in Russia, there is a high risk of virus introduction and spread in healthcare settings, including among medical staff who are not immune to varicella zoster virus (VZV). The objective of this study is to assess the immunity of employees of a multidisciplinary hospital in Moscow to VZV. Materials and methods. A selective screening study was carried out. Venous blood serum samples were taken from 1546 hospital employees as material for detection of IgG antibodies to VZV antigens using a commercial solid-phase enzyme immunoassay (ELISA) test system "Vecto VZV-IgG". All employees were questioned to obtain information about their infectious and vaccine history in relation to VZV. Results and discussion. Screening for antibodies to VZV in the hospital workers revealed that 6.3% of those workers are not immune to VZV. The proportion of seronegative individuals was the highest (12.6 ± 2.4%) in the age group of 29 years and younger. VZV seronegative healthcare workers were found in various departments, but the presence of non-immune individuals among the staff of the obstetrics and gynecology departments (6.5%) is of epidemiologic concern. The results of the survey showed that documented data on infection and vaccination history cannot be used to assess the protection of healthcare workers against VZV infection. Conclusion. The results of serologic screening for antibodies to VZV made it possible to identify a significant number of susceptible employees of the multidisciplinary hospital. In order to prevent the formation of multiple epidemic foci of varicella in medical organizations, it is advisable to include anti-VZV testing of medical staff in the state prevention programs with subsequent vaccination of non-immune individuals.

The Omicron strain is currently the main dominant variant of SARS-CoV-2, with a large number of sublineages. In this article, we present our experience in tracing it in Russia using molecular diagnostic methods. For this purpose, different approaches were used; for example, we developed multiprimer panels for RT-PCR and Sanger and NGS sequencing methods. For the centralized collection and analysis of samples, the VGARus database was developed, which currently includes more than 300,000 viral sequences.