Peculiarities of the influenza viruses circulation and their properties during 2018-2019 epidemic season in Russia and countries of the Northern Hemisphere

Objective . To identify the drift variability of influenza viruses during the period of epidemic rise in the incidence of acute respiratory viral infections in the period 2018-2019. The biological and molecular-genetic properties of epidemic strains isolated in certain territories of the Russian Federation were studied and compared with data from the countries of the Northern Hemisphere. Materials and methods . A range of laboratory diagnostic methods has been applied, including immune fluorescence, RT-PCR, sequencing, methods for determining sensitivity to influenza drugs and receptor specificity. Results and discussion . The proportion of influenza viruses was as follows: A (H1N1) pdm09 - 53 %, A (H3N2) - 46 %, B - about 1 %. Cases of severe acute respiratory infections have most often been associated with influenza A(H1N1) pdm09 virus. According to antigenic properties, isolated strains corresponded to the properties of vaccine viruses (A/Michigan/45/2015 - by 99.6 % and A/Singapore INFIMH-16-0019/2016 - by 86 %). The heterogeneity of influenza A virus strains population was revealed as regards individual mutations in hemaglutinin. The influenza B virus population was equally represented by both evolutionary lines (B/Victoria and B/Yamagata-like). Receptor specificity was favorable for the course and outcome of the disease. Among 70 studied epidemic strains, no strains resistant to anti-neuraminidase drugs, oseltamivir and zanamivir, were detected. The article presents WHO recommendations on the composition of influenza vaccines for the countries of the Northern Hemisphere for 2019-2020, provides data on cases of human infection with avian influenza viruses A(H5N1), A(H5N6), A(H7N9) and A(H9N2).