And he kept track of how many people he gave the vaccines to, and then he kept track of what would happen to those people when a smallpox infection occurred in their community.

他与接种过牛痘的人保持联系,关注当天花在这些人周围肆虐时,他们身上发生了什么

耶鲁公开课 - 生物医学工程探索课程节选