Introduction. The coronavirus disease (COVID-19) pandemic was announced by WHO in February 2020. In the Khabarovsk Krai, the first three cases of the disease were diagnosed on March 19, 2020, these cases were imported from Argentina (transit through Italy). The epidemic process of COVID-19 in the Khabarovsk Krai is characterized by a slow increase in the incidence. During the period of time when the SARS-CoV-2 seroprevalence study was conducted the incidence rates varied from 35.9 to 39.1 per 100 thousand population. Within the next 5 weeks the incidence continued to increase, the maximum level was 67.3 per 100 thousand population. A statistically significant decrease in the incidence is noted in the first decade of August. The study of the SARS-CoV-2 seroprevalence among residents of the region was carried out from June 9 to June 21, 2020 during the period of increasing intensity of the epidemic process of COVID-19 infection.Aim. To determine the level and structure of herd immunity to SARS-CoV-2 virus among the population of the Khabarovsk Krai during the period of intensive spread of COVID-19.Materials and methods. The study was conducted as a part of the first stage of a large-scale Rospotrebnadzor project to assess the herd immunity to SARS-CoV-2 virus among the population of the Russian Federation, taking into consideration the protocol recommended by WHO. The selection of volunteers for the study was carried out by the method of questionnaires and randomization by random sampling. The results of a survey of 2675 individuals were included into analysis. The number of volunteers in all age groups was similar.Results. The results of the study showed that the herd immunity to SARS-CoV-2 in the total population of the Khabarovsk Krai was 19.6%. The maximum level of herd immunity was observed in children 14–17 years old (34.4%), children 7–13 years old (24.8%), and people over 70 years (22.6%). The highest level of seropositivity, except for the children and the elderly, was found among educational workers (26.7%). The lowest level of seropositivity was found in the military (8.7%) and the unemployed (8.3%). There were no statistically significant differences in the level of seroprevalence between men and women.Conclusions. The results of the seroepidemiological study demonstrated that in the Khabarovsk Krai, the presence of the contacts with COVID-19 patients is associated with the 1.4-fold increase in the likelihood of the seroconversion. Antibodies were detected in 58.9% of the past COVID-19 cases. In individuals with the previous positive PCR test result, antibodies were detected in 50% of cases. A high rate of asymptomatic infection, up to 93.7%, was observed among seropositive volunteers.

Представлены результаты исследования бактериальной микрофлоры двух групп пациентов, больных внебольничной пневмонией («Covid+», N=86 и «Covid–», N=87). Обе группы характеризуются высоким уровнем выделения бактериальной флоры (81,4% и 74,7%), в том числе общепринятых возбудителей внебольничных пневмоний, существенной частотой выделения грибов рода Candida и микробных ассоциаций. Группа больных «Covid+» характеризуется более широким спектром определяемых возбудителей, выявлением полирезистентных грамотрицательных энтеробактерий – продуцентов БЛРС, грамотрицательных неферментирующих полирезистентных бактерий, более выраженным проявлением микробных ассоциаций. В группе наблюдения «Covid-» лекарственноустойчивая флора представлена только стафилококками групп MRSA, MRSE и др.

Introduction. Molecular-genetic monitoring of human immunodeficiency virus (HIV) drug-resistant strains circulation as well as analysis of territorial peculiarities of different genetic variants prevalence of the virus is a crucial part of epidemiological surveillance over HIV-infection spread. Objective of the research - to analyze the prevalence of HIV-1 genetic variants among HIV-positive people living in different constituent entities of the Far Eastern Federal District. Material and methods. Molecular-genetic analysis of the Pol-gene that is coding protease and a part of reverse transcriptase of HIV-1 was performed for a total number of 206 blood plasma samples. The biological material was collected from HIV-positive people living in Sakhalin, Magadan and Amur regions, Jewish Autonomous District, Khabarovsk region, Republic of Sakha (Yakutia) and Chukotka Autonomous Region (constituent entities of the Russian Federation in the Russian Far East). Results. The research demonstrated that HIV-1 sub-subtype A6 continues to be dominant and comprises 72.1±3.1% of all isolated subtypes in the regions of the Russian Far East. HIV-1 subtype B was identified in 14 cases (6.8±1.8%) and subtype C in 4 cases (1.9±1.0%). Spectrum of HIV-1 recombinant forms was determined for some regions. We identified five types of HIV-1 circulating recombinant forms (CRF): CRF03_AB - 2 (0.9±0.7%), CRF02_AG - 8 (3.9±1.3%), CRF63_02A1 - 27 (13.1±2.4%), CRF11_cpx - 1 (0.5±0.5%), CRF01_AE - 3 (1.5±0.8%). High heterogeneity of the virus was registered in the Jewish Autonomous District. Discussion. The conducted research revealed genetic differences in the landscape of HIV-1 subtypes circulation as well as differences in HIV-1 recombinant forms distribution frequency in the Russian Far East. Current findings are due to expansion of migration flows that promote cross-border importation and further spread of different HIV-1 genetic variants among population of the Far Eastern Federal District. Conclusion. The conducted research revealed that the molecular-genetic monitoring of HIV-1 genovariants should involve not only regions with high HIV-abundance but also with low HIV-prevalence and incidence.

Проведен анализ научных публикаций по вопросам основ патогенеза, лабораторной и рентгенологической картины пневмоний, а также вопросов ко-инфицирования у больных с SARS-CoV-2. На основе имеющихся в мировой научной литературе сведений дана оценка чувствительности методам компьютерной томографии и полимеразной цепной реакции. Наряду со сбором эпидемиологического анамнеза, обоснована необходимость применения как лабораторных, так и лучевых методов диагностики для наиболее достоверного выявления пациентов с новой коронавирусной пневмонией. Ключевые слова: SARS-CoV-2, пневмония, полимеразная цепная реакция, компьютерная томография, ко-инфекция

Current study was aimed at investigating prevalence of overt and occult hepatitis B infection in HIV-positive individuals as well as molecular-epidemiological characteristics of the circulating hepatitis B virus (HBV) strains in the Far Eastern Federal District (FEFD). A total number of 297 blood serum/plasma samples obtained from HIV-positive patients residing in the FEFD were enrolled in the study. The first control group included 351 blood serum/plasma samples of general population without indication on HIV and HBV-infection that underwent laboratory check up at the Centers for AIDS Prevention and Control. After evaluating the group of HIV-positive patients 20 HIV-HBV positive samples were selected for further detailed analysis. The second control group included 43 patients with chronic hepatitis B. All groups were age and gender-matched. The research included serological and molecular-genetic (real-time PCR, positive for HBV DNA samples underwent clonal sequencing of PCR-amplified HBV P/S gene) assessment of the biological material followed by a phylogenetic analysis of the HBV sequences. Our research revealed that HIV-positive patients are exposed to a higher risk of HBV infection compared to general population enrolled in the study, which is evident from the prevalence of anti-HBcAg antibodies in the groups examined. HIV-positive vs. first control group was positive for anti-HBcAg antibodies at higher rate (35.02%, CI 95: 29.5940.45% versus 22.22%, CI 95: 17.8726.57%, p = 0.0003). Abundance of ongoing HBV-infection markers was also higher in HIV-positive individuals compared to general population (6.73%, CI 95: 3.889.58% versus 0.85%, CI 95: 01.81%, p = 0.0001, respectively). Should be noted, that HBsAg-negative HBV infection in HIV-positive patient cohort comprised 1.01% (CI 95: 02.15%) whereas in general population this index was as low as 0.28% (CI 95: 00.84%). Virus hepatitis С and D were revealed at higher rate in HIV-positive individuals compared to patients with HIV-negative chronic HBV infection (p = 5.84 107 and p = 0.000001 respectively). HCV and HDV prevalence rates comprised 50.0% (CI 95: 27.4677.46%) and 40.0% (CI 95: 17.9762.03%) in HIV-positive patients. Similar indices in control group were 4.65% (CI 95: 010.94%) and 4.65% (CI 95: 010.94%), respectively. The phylogenetic analysis of the six isolated HBV sequences showed that the five samples belonged to genotype D, with dominant subtype D2 (verified in 4 cases). Further, HBV genotype С was detected only in one case. The obtained data indicate a necessity for further in-depth diagnostic examination of viral hepatitis in HIV-positive patients to lower a risk of developing life-threatening complications as well as preventing hepatitis spread in human population.

The aim: to study the structure and dynamics of population immunity to SARSCoV-2 of the population of the Southern Regions of the Far East (SRFE): Khabarovsk, Primorsky Krai and Amur Region during the COVID-19 epidemic in 2020.Materials and methods. The work was carried out according to the program for assessing population immunity to SARS -CoV-2 of the population of the Russian Federation according to the methodology developed by the Rospotrebnadzor with the  participation of the St.  Petersburg Pasteur Institute. The study was approved by  the  ethical committee of the St.  Petersburg Pasteur Institute. The selection of participants was carried out by a questionnaire method using cloud technologies. The  volunteers were randomized by age by stratification into 7  age groups: 1–17, 18–29, 30–39, 40–49, 50–59, 60–69, 70+ years old. Territorial randomization consisted in limiting the engaging of volunteers – no more than 30 people from one enterprise. After the initial cross-sectional study, a 3-stage seromonitoring was carried out, in which the same volunteers participated. Antibodies to the SARS-CoV-2 nucleocapsid were determined in peripheral blood serum by the enzyme immunoassay using an appropriate set of reagents produced by the State Scientific Center for Medical and Biological Sciences of the Rospotrebnadzor (Obolensk). Statistical analysis was performed using the Excel package. The confidence interval for the proportion was calculated using the A. Wald, J. Wolfowitz method with A. Agresti, B.A. Coull’s correction. The statistical significance of the differences was calculated online using a specialized calculator. The statistical significance of the differences was assessed with a probability of p˂ 0.05, unless otherwise indicated.Results. In a comparative analysis, the highest morbidity was observed in the Khabarovsk Territory, the lowest – in the Primorsky Territory. The level of seroprevalence among the population of the region was 19.6 % (95 % CI: 18.2–21.1) in  the  Khabarovsk Territory, 19.6  % (95  %  CI: 18.1–21.2) in the Primorsky Territory19,6 % and 45,5 % (95 % CI: 43.7–47.3) in the Amur region. The highest seroprevalence was noted among 1–17 years old children, mainly due to the subgroup of 14–17-years-olds. The smallest proportion of seropositive was found among 40–49-year-olds in the Khabarovsk Territory (14.7 %, 95 % CI: 11.2–18.6), 18–28-yearolds in the Primorsky Territory (13.3 %, 95 % CI: 10.0–17.1) and 30–39-year-olds in the Amur Region (36.3  %, 95%  CI:  31.7–41.6). No statistically significant dependence of  seroprevalence on territorial and occupational factors has been established, with the exception of an increase in the proportion of seropositive medical workers in Primorsky Territory. In the process of 3-stage seromonitoring, a regular increase in the proportion of seropositive people was revealed in all SRFE. The resulting tendency is correctly described by a second-order polynomial. A relationship was revealed between the number of convalescents and persons in contact with them, which made it possible to calculate the base reproductive number (R0) in the range from 1.4 (Primorsky Territory) to 2.4 (Amur Region). Analysis of seroprevalent volunteers showed that the number of asymptomatic individuals varied from 94.1 % (95 % CI: 92.8–95.3) to 98.3 % (95 % CI: 98.8–99.2). This indicates that most of the volunteers had COVID-19 asymptomatically.Conclusions. A comparative study showed the prevalence of seroprevalence in the Amur Region compared with the Khabarovsk and Primorsky Territories. The relationship between the number of convalescents and persons in contact with them was noted. The value of the base R0 is calculated. It has been shown that more than 90 % of seropositive individuals in the COVID-10 SRFE were asymptomatic.

Relevance. Pandemic of the new coronavirus infection has become a challenging issue for world healthcare system. Control of the epidemic process is one of the main priorities in combat against new coronavirus disease Aim. The research highlights the issue of asymptomatic carriers of the new coronavirus disease. Conclusions. It was revealed that patients with asymptomatic form of COVID-19 have a less lasting immunity response compared with those that have had clinically active forms of the infection. In order to determine pathogenetic process and fully understand formation of the immune response, it is necessary to study both humoral and cellular immune responses in patients diagnosed with COVID-19. In order to select most optimal anti-epidemic measures to contain the further spread of the disease, including asymptomatic carriage, it is necessary to establish SARS-CoV-2 reproduction index and determine minimal infective dose of SARS-CoV-2.

Objective: to study the bacterial microflora in the sputum of patients with pneumonia caused by SARSCoV-2 or other pathogens.Materials and methods. The bacterial microflora of sputum of 173 patients with pneumonia admitted to hospitals in Khabarovsk and the Khabarovsk Territory in May – June 2020 was examined. Detection of RNA of the SARS-CoV-2 virus was carried out by PCR with the Vector-PCRRV-2019-nCoV-RG test system (manufactured by the State Scientific Center of VB “Vector”, Koltsovo). Determination of the DNA of mycoplasmosis agents and chlamydia was carried out with the test system “AmpliSens® Mycoplasma pneumoniae/Chlamydophila pneumonia” (manufactured by CRIE). Statistical data processing was performed using the Excel program. Results and discussion. Both groups of patients (Covid-19+ and Covid-19–) had high levels of bacterial flora isolation (81.4 and 74.7 %) including common pathogens for community-acquired pneumonia as well as notable detection frequency of Candida spp. and microbial associations. The group of Covid-19+ patients demonstrated a wider range of detected pathogens, was positive for poly-resistant gram-negative Enterobacteriaceae, non-fermenting gram-negative poly-resistant bacteria, with more expressed manifestation of microbial associations. In the group of Covid-19– participants drug-resistant microflora was presented only by MRSA and MRSE  staphylococci.