Atypical epidemic of influenza and acute respiratory illness (ARI) in Ukraine in 2009/2010

Background: The „new“ 2009 A(H1N1) pandemic influenza has spread to more than 213 countries worldwide and caused 16,931 deaths since its first detection in April 2009. In Ukraine influenza/ARI are normally characterized through seasonality, mass coverage and longstanding cycling. The 2009/2010 influenza season started significantly earlier than usual, marked by rapid increase in consultations, fatal cases of pneumonia complications and cases of 2009 pandemic influenza. Methods: To graphically describe the 2009/2010 epidemic of influenza/ARI in Ukraine, official data (29.10.09–23.03.10) published by Ministry of Health were collected, collated and analysed. Graphs were used to present the temporal and geographical trends in the incidence of influenza/ARI and in consultation rates. Results: As of March 23, 2010, 6,195,446 cases (13.5% of the total population) of influenza/ARI have been reported; of which 4,475,370 were hospitalized. The epidemic displayed two earlier peaks (during 2009 44–45 and 50–52 weeks) and one later peak (during 2010 3–4 weeks). The most remarkable features of these epidemics were a rapid increase in number of consultations in the west as well as fatal pneumonia cases among younger population with no underlying medical conditions. In total 1,121 fatal cases of influenza/ARI were registered. The 2009 pandemic influenza was detected in 466 cases, of which 202 were fatal. Conclusions: The early peaks of influenza in the west of Ukraine coincided with the spread of 2009 pandemic influenza in some parts of Western Europe, to which high numbers of working migrants travel on regular basis. The sudden decline of temperature as well as no epidemic of influenza in this region during the last several years may have weakened the immunity of population against the influenza and hence facilitate the rapid increase in influenza cases. Ukraine experienced moderate to severe impact of the epidemic on its hospital and intensive care system, showing that pandemic preparedness planning is an upcoming public