You could have good humours and you could have bad humours and if those humours, whatever they are, got out of balance then you got sick if you had too many bad ones compared to good ones.

你可以有正常的体液,也可以有异常的体液,如果这些体液,不管体液究竟为何物,当体液失衡,你就会生病,即在异常体液比正常体液多时就会生病

耶鲁公开课 - 生物医学工程探索课程节选

So you need hundreds of millions of doses, at least, and you need a way to distribute that around the world, and you need a way to keep track of who got sick and who didn't after they got vaccinated.

至少需要上亿支的剂量,还得有办法将疫苗运送到世界各地,你还要一种方法进行跟踪,在接种疫苗之后谁得病了和谁没得病

耶鲁公开课 - 生物医学工程探索课程节选