Smallpox affected world history hundreds of years ago, and it was a disease that was common in Europe, but not common in the Americas until the Americas were colonized.

天花影响了几个世纪前的历史,这种病在欧洲很常见,但在美国不多见,直到美国成为殖民地

耶鲁公开课 - 生物医学工程探索课程节选