Global health: Pandemic preparedness and response - Lessons from the H1N1 influenza of 2009

摘要

A NUMBER OF VIRUSES HAVE PANDEMIC POTENTIAL. FOR EXAMPLE, THE coronavirus responsible for the severe acute respiratory syndrome (SARS), which first appeared in southern China in November 2002, caused 8096 cases and 774 deaths in 26 countries before coming to a halt by July 2003 mainly owing to isolation and quarantine. In terms of persistence, versatility, potential severity, and speed of spread, however, few viruses rival influenza virus. Endemic in a number of species, including humans, birds, and pigs, influenza virus causes annual outbreaks punctuated by occasional worldwide pandemics, which are characterized by sustained community spread in multiple regions of the world. Beyond spread, the degree to which a pandemic is defined according to the severity of the disease, or whether it may be simply described as often producing many illnesses and deaths, remains ambiguous. At its worst, pandemic influenza can be catastrophic: the great influenza pandemic of 1918-1919 is estimated to have infected 500 million persons worldwide and to have killed 50 to 100 million persons. In a typical year of seasonal outbreaks in the Northern and Southern Hemispheres, influenza virus causes as many as 5 million cases of severe illness in humans and 500,000 deaths.