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.

Проведен ретроспективный анализ проявлений эпидемического процесса энтеровирусной инфекции в Хабаровском крае в предшествующий наводнению семилетний период. Показано наличие предпосылок возможного осложнения эпидемиологической обстановки в период чрезвычайной гидрологической ситуации 2013 г. В крае из года в год сохраняется стабильно неблагополучная ситуация по заболеваемости энтеровирусными инфекциями, наблюдаемая при благоприятных климатических условиях -высоких температурах воздуха и воды поверхностных водоемов, высокой влажности воздуха. Поддержанию эпидемического процесса в течение всего года способствуют «здоровое» вирусоносительство и обширное распространение энтеровирусов в водных объектах внешней среды. Отмечена широкая циркуляция различных генотипов энтеровирусов, в том числе имеющих высокую степень генетического сходства со штаммами, зарегистрированными на сопредельной территории Китайской Народной Республики.Ключевые слова: энтеровирусная инфекция, Хабаровский край, эпидемический процесс, заболеваемость, штаммы энтеровирусов.Carried out has been retrospective analysis of epidemiological process manifestations as regards enteroviral infection in the Khabarovsk Region over the period of 7 years, prior to rainfall floods in 2013. Revealed is the possibility of aggravation of epidemiological situation during hydrological emergency situation. The premises are as follows: persistent due to specific climate conditions prevalent in the Khabarovsk Territory (high air and surface water temperatures, and high humidity rates) unfavorable epidemiological situation on enteroviral infections, virus-carriage in "healthy" people and extensive dissemination of enteroviruses in the water bodies of ambient environment. Moreover, widespread circulation of different enterovirus genotypes, including the isolates with high genetic similarity to the strains identified earlier in the adjoining People's Republic of China, takes place.

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 review presents data on epidemiological risks concerning worldwide spread of enterovirus infection due to intensified migration flows. Outbreak incidence of the most frequently registered forms of enterovirus infection – hand, foot and mouth disease (HFMD) –was analyzed. At the present time, Coxsackievirus A6 plays ever-greater significance in HFMD incidence. The article summarizes currently available scientific data on atypical Coxsackievirus A6-infection clinical manifestations. Details on the tense epidemiological situation concerning Enterovirus D68 that can be the cause of acute flaccid paralysis/myelitis are presented. According to latest recommendations, the molecular genetic techniques are the «golden standard» in diagnostics of enterovirus infection.