Development of the influenza epidemic in season 2011-2012 in some areas of Russia: results of activity of the Influenza Etiology and Epidemiology Center of the Ivanovsky Institute of Virology]

The results of analysis of the peculiarities of the epidemic 2011-2012 development in the areas of 10 cities of Russia obtained by basic laboratories of IEES on the base of D.I. Ivanovsky Research Institute of Virology, Ministry of Public Health and Social Development of Russia, are presented. The increasing ARD morbidity caused by the influenza viruses was detected rather late--in February-March 2012. The highest indices of the morbidity were detected during weeks 10-13 followed by decreasing to threshold levels by week 27. Children 0-2 and 3-6 years old were involved the most, meantime the high rate of hospitalization was found for 15-64 years old aged group (25%). Influenza A(H3N2) and B viruses were the cause of the epidemic. The results of studies of the antigenic and genetic properties of the influenza strains showed most of them to be close relatives to the vaccine strains. Some heterogeneity of circulating strains and their drift variants were found as well. All tested strains were sensitive to arbidol, oseltamivir and zanamivir, and saved resistance to rimantadine. The ratio of ARD viruses was comparable with the last epidemic seasons.