Influenza A(H1N1) pandemic: 2 years after

摘要

In 2009, the emergence of the new H1N1 influenza virus saw the world brace itself for the first influenza pandemic since 1968. Two years after, it is time to evaluate the situation of that Influenza A(H1N1) pandemic and its combat measures.First, alert level was raised rapidly from level 3 to level 6 in 6 weeks. On 25 April 2009, the WHO declared a level 3 Influenza Pandemic Alert. Three days after, level 4 alert was declared due to international spread of clusters of human-to-human transmission. The continuous confirmation of new cases in various countries required the WHO to raise the pandemic alert to level 5, less than 1 week after declaring level 3. The maximum alert response was declared on the 11~(th) of June, meanwhile most human infections appeared to be mild [1]. Recent study analysed the records of past influenza outbreaks to determine a definition for pandemics. The authors concluded that defining an influenza pandemic on the early observations may be adequate to declare an alerting response but doesn't assure worldwide spread or excess mortality [2].