CNN Vietsub - Vi-rút lây lan như thế nào? (How does a virus spread?) скачать в хорошем качестве

CNN Vietsub - Vi-rút lây lan như thế nào? (How does a virus spread?)

There are plenty of ways. It could be sneeze, a handshake, or sexual contact to name a few. Then there’s our habits, washing our hands, not touching our face. Even the climate may play a role in determining how far and how fast an infection spreads. Scientists have summed up how far an infection can spread with a number. It’s called R0 . A number greater than 1 indicates it’ll grow. Less than 1 indicates the outbreak will die out. Scientists determined the number with a formula that bring together all the environmental and biological factors. This is how it looks in reality. An infection is introduced to a human, from an animal and let’s say. The bigger that R0 number, the more people a virus can infect. So an R¬0 of 2 means that patient zero will, on average, infect 2 other people who, in turn, can infect another 2 people, and so on. An infection like measles sits higher up the spectrum with an R0 of between 12 and 18. At the lower end is something like Ebola with an R0 number of 1,5 to 2,5. And while the flu varies from year to year, one study reports it average to 1,2. But various factors change, so, too, does the R0. Take SARS, when it first emerged, SARS spread rapidly with a high R0. But people were only contagious once symptoms started showing. Once people were informed about the symptoms, they started coming to hospital earlier. People could check themselves into hospital before infecting other people, pushing the R0 number below 1. And that is how a virus spread.    • CNN Vietsub - Vi-rút lây lan như thế nào? ...   Source CNN.