What is a pandemic?
什么叫大流行病？
What is a pandemic? To understand that, we need to first understand where they start.
什么叫大流行病？要想知道答案，我们首先需要了解一下它是如何产生的。
Jennifer Rohn (University College London) An epidemic is simply an outbreak of inflection in a localized area. A pandemic is when that inflection spreads to multiple countries around the world.
Jennifer Rohn (伦敦大学学院)： 流行病只是在局部地区爆发的一种传染病，当流行病的疫情蔓延到全球多个国家时，即为大流行病。
And while on the one hand, we are better protected than before. On the other, our changing society brings together a host of other challenges.
一方面，我们比以前得到了更好的保护；另一方面，我们不断变化的社会又为我们带来了一系列挑战。
Jennifer Rohn (University College London)： In this day and age, all you need is one person at the airport and you can infect the whole world.
Jennifer Rohn：当今这个时代，只要一个病毒携带者出现在机场，疫情就可能会扩散到全世界。
The majority of pandemics to date have been strains of influenza Through pandemics can be any type of infection, usually a virus. Many new or novel viruses come from animals. They can pass on to humans after close contacts and a process called zoonotic spillover.
迄今为止的大流行病大多是流感的菌株。虽然大流行病可能体现为任何方式的感染，但其中主要还是病毒型感染。很多新型病毒都来源于动物，它们可以通过密切接触的途径传播给人类，这种传播过程叫做人畜共患。
Jennifer Rohn (University College London)： And when that happens, sometimes the virus is not very transmittable, because it is suited to circulating only in animals. But sometimes we see ones that can transmit from person to person and they can be quite efficient at doing this. And in that case, an outbreak can become an epidemic as it grows and there is a chance that it could spread more widely.
Jennifer Rohn：而且当这种情况出现时，有时候这种病毒的传播能力并不强，因为它只会在动物之间传播。但有时候，我们会发现一些病毒可以在人之间传播，而且他们的传播能力很强。随着病毒的传播，疫情可能会爆发成为流行病，还可能会更广泛地传播，进而爆发成大流行病。
This is what happened in the 2009 swine flu pandemic. A pig influenza virus is moved into people. Pig viruses are similar to human viruses and that allows human to human transmission to happen quicker. More than a decade has passed since the 2009 pandemic and the world’s population has grown, as have the risks of passing viruses between people.
这就是2009年猪流感大流行时的情形。一种猪流感病毒传播给了人类。猪的流感病毒与人的流感病毒相似，这使得这种病毒在人与人之间传播的更快。2009年的猪流感大流行已经过去十多年了，世界上的人口越来越多，人与人之间的病毒传播风险也越来越大。
Jennifer Rohn (University College London)： We are getting more and more people on the planet, we are having more globalization. People are travelling from country to country more than ever before. So, these are kind of things that will cause pandemics to happen.
Jennifer Rohn：地球上的人越来越多，全球化程度也越来越高。人们从一个国家到另一个国家的旅行也比以往任何时候都多，这些都是可能会导致大流行病发生的事情。
Medicine technology and communication have all improved with time, and serious outbreaks require international cooperation. But experts say the real question isn’t if a new pandemic strikes but instead how bad it could be.
随着时间的推移，医学技术和通讯技术都在进步，疫情严重时需要国际间的共同合作。但专家表示，目前真正需要关注的问题不在于是否会有新的大流行病爆发，而在于爆发的大流行病会带来多么严重的后果。
