R0       
noun [ U ] /ˌɑː ˈnɔːt/ /ˌɑːr ˈnɑːt/ (mainly UK also R)
 (疾病的)基本传染数
symbol for reproduction number: the average number of people that one person with a particular disease infects
  R0 describes how many cases of a disease an infected person will go on to cause. R0显示的是一个患病者会传染给多少人。 
 If R0 is 3, then on average every case will create three new cases. 如果R0是3,就说明平均每个患病者会制造3个新的病例。 
 - More examples
 - Governments around the world keep talking about R0.
 - Is the basic reproductive number (R0) for measles viruses observed in recent outbreaks lower than in the pre-vaccination era?
 - R0 is the average number of people who will catch the disease from a single infected person, in a population that’s never seen the disease before.