Portrait of a year-old pandemic

摘要

One year ago this month, the world watched with trepidation as a novel influenza A virus, to which the global population had little or no immunity, emerged in Mexico and the United States. In the weeks that followed, the H1N1 'swine flu' virus spread rapidly to countries worldwide, leading the World Health Organization (WHO) on 11 June 2009 to officially declare the first flu pandemic in more than 40 years. Nature looks at the lessons learnt from H1N1, and how they will help scientists and health authorities to handle the next flu pandemic.