And he hypothesized that they were getting the disease in cows, which the disease from cows that caused a milder disease than smallpox, and that protected them from getting the more severe forms of smallpox later.

他假定奶牛将这种疾病传染给挤奶女工,这种源自奶牛的疾病比天花更温和,它保护女工们,免受更为严重的天花感染

耶鲁公开课 - 生物医学工程探索课程节选