WHO did not change its definition of pandemic influenza for the simple reason that it has never formally defined pandemic influenza.

世界卫生组织并没有改变其对大流行性流感的定义，原因很简单，那就是其从未正式定义大流行性流感。

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Whats the right usage of antibiotics and whats the principle for treating influenza are two simple and representative questions.

抗生素的正确用法是什么？和感冒的治疗原则是什么？这是两个比较有代表性的问题。

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The CDC also has its own simple app called FluView that plots the volume of influenza-like illnesses by state.

CNN: Tracking the flu with technology and Twitter

Prof Wendy Barclay, chair in influenza virology at Imperial College London, said other more complex viruses make proteins at different times during replication, but what is clever is that influenza can do this in such a simple way.

BBC: Flu virus 'knows when to attack'