Influenza (AH1N1v) pandemic 2009: an update.

摘要

In a previous editorial, we described the outbreak of the first influenza pandemic of the 21st century, which was caused by a new variant of the AHlNlv virus. On the basis of the first observations, we attempted to forecast the most probable evolution of this phenomenon [1]. Three months later, it now seems useful to take stock of what has happened, in order to evaluate and utilize the experience gained. In those three months, the AHlNlv virus spread to almost all countries in the world. However, the epide-miological scenario differed on account of factors that cannot all be explained. In North America (USA [2], Mexico [3] and Canada [4]), where the first outbreaks were reported, an initial rapid rise in the number of cases (May, 2009) was followed by a more gradual spread of the disease. At the end of August, however, infections again accelerated and continued to rise up to the end of September. The hospitalization rate of laboratory-confirmed cases among 5-17-year-old patients exceeded that of seasonal influenza, while it was markedly lower in the over- 65 age-group.