FEATURES OF EPIDEMIC PROCESS OF INFLUENZA A(H1N1)PDM09 AND A(H3N2) IN RUSSIA FROM 2009 TO 2017

The goal of this work is to compare the key parameters of influenza epidemics of different etiology. Four epidemics of influenza with predominance of influenza A(H1N1)pdm09 and 4 epidemics of influenza A(H3N2) were analyzed using the database of the Federal State Research Institute of Influenza on morbidity, hospitalization, deaths from influenza in 59 cities in the period from 2009 to 2017. The intensity of epidemics involving the influenza A(H1N1)pdm09 decreased from high to medium, while the intensity of epidemics of influenza A(H3N2) increased from low to medium. In the epidemic of influenza A(H1N1)pdm09 in the total population, the incidence of influenza and ARI decreased by a factor of 1.6, while the mortality among patients decreased by a factor of 1.7 in all age groups, except for those over 65 years, for whom the incidence and mortality increased by factors of 1.4 of 2.3, respectively. In the epidemic of A(H3N2), a trend for increasing morbidity and mortality was more pronounced among individuals older than 65 years. Pandemic influenza remains the leading cause of deaths. Among the dead in the epidemic of influenza A(H1N1)pdm09, the proportion of young individuals decreased (including a fourfold decrease of lethality in pregnant women), while the proportion of persons over 65 years increased 7.8 times; in the epidemic of influenza A(H3N2) only 2.5-fold increase was observed. In the epidemic of influenza A(H1N1)pdm09, the proportion of lethality increased among people with cardiovascular diseases and diseases of the internal organs; in the epidemic of influenza A(H3N2), the proportion of lethality increased among people with immunodeficiency, diseases of the internal organs and respiratory system.