So, it's awkward to have to wait for a cow to get infected before you can vaccinate a population.

在给人们预防接种之前,你只有干等着,直到有一头奶牛感染了病毒才行

耶鲁公开课 - 生物医学工程探索课程节选

None of you got smallpox vaccinations, because once a country was certified to be smallpox free, there was no reason to-- there was no reason to vaccinate people any longer.

你们当中没人接种过天花疫苗,因为一旦一个国家确认不再有天花,就没有理由,就没有理由再给人们接种

耶鲁公开课 - 生物医学工程探索课程节选

And it would be really difficult to vaccinate a wildlife.

而给野生动物接种是非常困难的

耶鲁公开课 - 生物医学工程探索课程节选

We'll think about it in section, how you don't need to vaccinate everybody, but you just need to vaccinate a critical number in order to stop the disease from progressing through a community.

我们在讨论会上讲这个,为什么不需要给每个人都接种,但你只需要让接种人数达到一个临界值,就能阻止这个疾病在社会中传播

耶鲁公开课 - 生物医学工程探索课程节选

Because if it was a disease that was carried by both humans and squirrels, for example, then in order to get rid of it on the planet, you'd have to vaccinate not only all the people but all the squirrels, right?

因为假如人和松鼠都能携带,某种疾病的话,想要把这种疾病从地球上清除,不仅要给所有人接种疫苗,还要给所有松鼠接种疫苗

耶鲁公开课 - 生物医学工程探索课程节选