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Epidemiological Aspects of Seasonal and Pandemic Influenza in Recent Years and Emerging Viruses

[ Vol. 3 , Issue. 1 ]


Daniela Loconsole and Maria Chironna   Pages 15 - 24 ( 10 )


Influenza is a major public health problem worldwide. Epidemiological and virological surveillance has been demonstrated to be crucial for prevention of both seasonal and pandemic influenza. Recent influenza seasons have been characterized by the circulation of the strain A(H1N1)pdm09. It was identified for the first time in 2009 and accounted for the most recent influenza pandemic. In spite of moderate mortality rates observed during 2009 influenza pandemic, quite interestingly severe cases of influenza by the new pandemic strain A(H1N1)pdm09 were more frequent in young adults, who were previously healthy and free of risk factors. Of note, dissemination of influenza A(H3N2) virus with both antigenic and genetic drifts was mostly predominant in 2014-2015 influenza season. The variant A/Switzerland/9715293/2013(H3N2) replaced A/Texas/50/2012(H3N2) in vaccine formulation of season 2015-2016. Recent influenza seasons in South Italy (Apulia region) were characterized by lower and later incidence peaks respect to those of Northern Italy probably due to differences in climate. Influenza vaccine coverage rates in Apulia steadily declined in general population, especially in individuals ≥ 65 years, creating concern in health authorities. Avian influenza viruses (AIVs) such as H5N1, H7N9, H9N2 and H10N8 are able to disseminate to domestic poultry and then to humans from natural sources. Therefore, these viruses are considered as emerging with a special concern related to their potential to cause next influenza pandemic.


A(H1N1)pdm09, A(H3N2), avian influenza virus, epidemiology, influenza A virus, influenza B virus, pandemic, South Italy, surveillance.


Department of Biomedical Sciences and Human Oncology, School of Medicine, University of Bari “A. Moro”, Bari, Italy.

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