And so even people that got vaccinated, most of us either have questionable or no protection against the virus at this point.

所以就算那些接种过天花疫苗的人,到那时候也不一定,或者压根无法抵御病毒

耶鲁公开课 - 生物医学工程探索课程节选

And they did this by taking-- they recognized that somehow, if you had a mild exposure to the disease, your body could then develop protection against more severe forms of the disease.

他们通过用,他们通过某种方式意识到,如果较轻微地得过这种病,你的身体会发展保护机制,来抵挡更为严重的疾病

耶鲁公开课 - 生物医学工程探索课程节选