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。