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Understanding the evolutionary dynamics of influenza A virus is central to its surveillance and control. While immune-driven antigenic drift is a key determinant of viral evolution across epidemic seasons, the evolutionary processes shaping influenza virus diversity within seasons are less clear. Here we show with a phylogenetic analysis of 413 complete(More)
BACKGROUND The first pandemic season of A/H3N2 influenza virus (1968/1969) resulted in significant mortality in the United States, but it was the second pandemic season of A/H3N2 influenza virus (1969/1970) that caused the majority of deaths in England. We further explored the global pattern of mortality caused by the pandemic during this period. METHODS(More)
The European Paediatric Influenza Analysis (EPIA) project is a multi-country project that was created to collect, analyse and present data regarding the paediatric influenza burden in European countries, with the purpose of providing the necessary information to make evidence-based decisions regarding influenza immunisation recommendations for children. The(More)
While air travel contributes to the spread of infl uenza epidemics, the magnitude of impact is not clear compared to other factors—a crucial issue when considering a fl ight ban in the context of pandemic planning. Recent modeling efforts simulating the spread of pandemic infl uenza have concluded that such an intervention would matter little relative to(More)
T he global burden of infl uenza on morbidity and mortality is considerable, with an estimated 1 million annual deaths worldwide [1]. In temperate regions, there are clear seasonal variations in the occurrence of infl uenza, with a marked peak in cold winter months [2]. In contrast, seasonality is less defi ned in tropical regions—here, there is high(More)
The H1N1 subtype of influenza A virus has caused substantial morbidity and mortality in humans, first documented in the global pandemic of 1918 and continuing to the present day. Despite this disease burden, the evolutionary history of the A/H1N1 virus is not well understood, particularly whether there is a virological basis for several notable epidemics of(More)
BACKGROUND Mexico's local and national authorities initiated an intense public health response during the early stages of the 2009 A/H1N1 pandemic. In this study we analyzed the epidemiological patterns of the pandemic during April-December 2009 in Mexico and evaluated the impact of nonmedical interventions, school cycles, and demographic factors on(More)
Influenza is an important cause of mortality in temperate countries, but there is substantial controversy as to the total direct and indirect mortality burden imposed by influenza viruses. The authors have extracted multiple-cause death data from public-use data files for the United States from 1979 to 2001. The current research reevaluates attribution of(More)
The winter seasonality of influenza A virus in temperate climates is one of the most widely recognized, yet least understood, epidemiological patterns in infectious disease. Central to understanding what drives the seasonal emergence of this important human pathogen is determining what becomes of the virus during the non-epidemic summer months. Herein, we(More)
The on-going debate about the health burden of the 2009 influenza pandemic and discussions about the usefulness of vaccine recommendations has been hampered by an absence of directly comparable measures of mortality impact. Here we set out to generate an "apples-to-apples" metric to compare pandemic and epidemic mortality. We estimated the mortality burden(More)