Past pandemic outbreaks have typically originated from animal viruses, before crossing over to humans.

过去的大流行病爆发通常起源于动物病毒，然后才传染给人类。

So what's interesting about coronaviruses is that they are animal viruses, probably primarily in bats.

SB：所以冠状病毒的有趣之处在于它们是动物病毒，可能主要存在于蝙蝠中。