[Peculiarities of the influenza and ARVI viruses circulation during epidemic season 2019-2020 in some regions of Russia]

INTRODUCTION

The surveillance of influenza viruses in ARVI structure and study of their properties in epidemic season 2019-2020 in Russian Federation are actual for investigations due to tasks of Global Influenza Strategy initiated by WHO in 2019.

MATERIAL AND METHODS

The data of epidemiological surveillance on influenza- and ARVI-associated morbidity and hospitalization in different age groups of population were analyzed; virological, genetic and statistical methods were used.

RESULTS

Preschool children were involved in epidemic the most. Meanwhile, the highest rate of hospitalization was observed in patients of 18-40 years old. Influenza A(H1N1)pdm09 virus dominated in etiology of ARVI in hospitalized patients and pneumonia. The role of respiratory viruses in severe cases of pneumonia and bronchoalveolar syndrome in children was shown. The differences in spectrum of circulating viruses caused ARVI in different regions of Russia were found. Influenza A(H1N1)pdm09 and B/Victoria-like viruses were the main etiological agents that caused of epidemic; its activity among all ARVI was 7.3 and 8.0%, respectively. The differences in antigenic properties of influenza A(H3N2) and B epidemic strains compared to vaccine viruses were found. The populations of epidemic strains were presented by following dominant genetic groups: 6B1.A5/183P for A(H1N1)pdm09, 3С.2а1b+137F for A(H3N2) and V1A.3 line B/Victoria-like for B viruses. The good profile of epidemic strains susceptibility to anti-neuraminidase inhibitors has been saved. The most of the studied influenza strains had the receptor specificity characteristic of human influenza viruses.

CONCLUSIONS

Obtained results identified the peculiarities of viruses caused the influenza and ARVI in epidemic season 2019-2020 in different regions of Russia. These results suggested the important role of influenza A(H1N1) pdm09 in severe cases and pneumonia in adults 18-40 years old. The continuing drift in influenza viruses was found, which, apparently, could not but affect the efficacy of vaccine prophylaxis and was also considered in the recommendations of WHO experts on the composition of influenza vaccines for the countries of the Northern Hemisphere in the 2020-2021 season.

[Immunoprophylaxis of infections of the upper respiratory tract in the frequently ill children]

The review of the clinical studies designed to evaluate the prophylactic effectiveness of ribosomal immunization is presented. It is shown that the application of the ribosomal vaccine ribomunyl causes a significant reduction in the occurrence of acute respiratory infections in the frequently ill children, lowers the frequency of exacerbation of chronic diseases of the upper respiratory tract, and allows to decrease the use of antibiotics. The authors emphasize the high therapeutic effectiveness and safety of preventive measures against respiratory infections in the frequently ill children with the use of the anti-influenza vaccine in combination with ribosomal immunization.

[Serodiagnosis in the surveillance of the influenza virus circulation during the development of the pandemic caused by the A (H1N1)pdm09]

The goal of this work was to present the data of the study of the peculiarities of the generation factors of humoral immunity in the response to the infection with the pandemic influenza A (HIN1) pdmO9 in patients with different epidemiological anamnesis. High ability of the influenza viruses to spread over closed communities and the transfer of the maternal antibodies to babies, including a pandemic strain of the influenza virus A (H1N1) pdm09, was confirmed. The results of this study showed that the immune response to the surface antigens of the influenza virus (hemagglutinin and neuraminidase) was formed during the natural infection with the pandemic strains of the influenza A (H1N1) pdm09 in more than a half of the cases simultaneously.

[Efficiency of the influenza A and B viruses isolation from nasopharyngeal swabs taken in the test tubes Sigma-Virocult (M40 Compliant, Sigma Virocult) and Virocult (M40 Compliant, Virocult) in 2010-2011 epidemic season]

The goal of this work was to compare the efficiency of the influenza A and B viruses Isolated during 2010-2011 epidemic season. The clinical samples were taken in the test tubes with the transport medium on the.basis of the medium EMEM and commercial test tubes Sigma-Virocult (M40 Compliant, Sigma Virocult) and Virocult (M40 Compliant, Virocult). The results of this work demonstrated higher efficiency of influenza A and B viruses isolation from nasopharyngeal swabs of the patients taken in the test tubes Sigma-Virocult (M40 Compliant, Sigma Virocult) and Virocult (M40 Compliant, Virocult) with the transport medium as compared with the efficiency of influenza strains isolation from nasopharyngeal swabs taken in test tubes with the medium EMEM with respect to all estimated indicators: efficiency of isolation, a passage of isolation and the titer of isolates. The possibility of the long-term storage of a clinical material at room temperature and at 4 degrees C was confirmed, without resorting to freezing, which is significant in the absence of the necessary equipment.

[Monitoring of the sensitivity of epidemic influenza virus strains isolated in Russia to etiotropic chemical agents]

The paper presents the results of studying the spectrum of influenza A and B viruses to rimantadine, arbidol, and oseltamivir and describes the methods used for these purposes for epidemiological surveillance. Different sensitivities to rimantadine were found among influenza A viruses. During the 2007-2008 season, the vast majority of influenza A(H3N2) virus strains were resistant to rimantadine (77%) while all influenza A(H1N1) virus strains preserved their resistance to this drug. The fact that the epidemic influenza A(H1N1) virus strains that carry the mutation responsible for resistance to the neuraminidase inhibitor oseltamivir (Tamiflu) circulated in the Russian Federation was first established. At the same time all the study influenza A(H1N1) virus strains preserved their susceptibility to rimantadine. The sensitivity of the epidemic strains to arbidol has been confirmed.

[Rimantadine and arbidol sensitivity of influenza viruses that caused epidemic morbidity rise in Russia in the 2004-2005 season]

The study of the activity of arbidol against epidemic influenza A and B virus strains (2002-2005) in the cultured MDCK cells showed the higher sensitivity of enzyme immunoassay than that of hemagglutination test. The influenza A virus strains tested, including those resistant to rimantadine (5 microg/ml), were sensitive to arbidol (10 microg/ml). The population of influenza B virus strains was heterogeneous in this indicator, 43% of the strains being less sensitive to arbidol. There was an increase in the number of rimantadine-resistant influenza A(H3N2) virus strains (10-18%) in our country during 3 epidemic seasons. The sequencing analysis of protein M2-endoding gene revealed the amino acid replacement of serine by asparagine in position 31, which is characteristic of rimantadine-resistant strains. Arbidol in combination with rimantadine potentiated the effect of viral reproduction in the cultured cells, as compared with the effect produced by the same concentrations of the drugs used alone.

[Evaluation of the immunogenic and reactogenic properties of vaccine "Euvax B" in persons aged 16-18 years in different geographical zones of Russia]

The comparative evaluation of the reactogenic and immunogenic properties of vaccine "Euvax B" in adolescents aged 16-18 years was carried out in factory housing estate Lvovsky, the Podolsk district, the Moscow region, and in the Yamalo-Nenets Autonomous District (AD): in towns Salekhard, Noyabrsk, Muravlenko, in housing estate Tarko-Sale. The evaluation demonstrated that the use of this vaccine in a dose of 20 mg/ml produced no postvaccinal complications and the frequency of postvaccinal reactions was insignificant. Postvaccinal anti-HBs were detected, on the average, in protective concentrations in 98.4 +/- 1.8% of the vaccines (99.0 +/- 1.9% in the Moscow region, 97.7 +/- 3.2% in the Yamalo-Nenets AD). In most of the vaccinated adolescents high concentrations of postvacinal anti-HBs were detected: in 51.4 +/- 9.7% of the vaccinees in the Moscow region and in 89.7 +/- 6.4% in the Yamalo-Nenets AD they exceeded 1,000 I.U./lit. The conclusion was made that in the territories located in subarctic latitudes vaccinal prophylaxis against hepatitis B was safe and highly effective and have no limitations connected with the conditions of the Far North.

[Specific prophylaxis of influenza in organized groups of children with the vaccine Vaxigrip]

The results of the open comparative study on epidemiological effectiveness and tolerance of the vaccine Vaxigrip, carried out in 109 children aged 2-15 years with different initial state of health, are presented. The index of epidemiological effectiveness of Vaxigrip was 4.09 (p < 0.05), the rate of epidemiological effectiveness--75.6% (p < 0.05). Vaxigrip was found to be well tolerated by both healthy children and those with different functional disturbances and chronic diseases. The study revealed that the use of Vaxigrip was not accompanied by any systemic postvaccinal reactions. High prophylactic effectiveness and good tolerance of Vaxigrip make it possible to recommend it for mass immunoprophylaxis of influenza in children.