Human-to-human transmission, limited or sustainable spread?

Zhong Nanshan, a renowned respiratory expert, confirmed on Jan 20 that the new coronavirus can be transmitted among humans. But there are two types of human-to-human spread: limited and sustainable.

The former refers to cases in which the virus spreads from one human to another, who is not able to further infect other humans. The latter refers to cases in which the virus can spread across generations, posing much greater threat to us. No cases of the latter scenario have been detected.