将近一个世纪，疫苗病毒(称牛痘)从手臂到手臂、从一个人身上转移到另一个人身上，问题是如何找到提供大量疫苗的方法，这个问题最终通过在牛胁腹部种植疫苗病毒的办法解决了。

The problem was to discover how to provide large amounts of vaccine. This was eventually solved by growing the vaccine virus on the flank of cows.

youdao

将近一个世纪，疫苗病毒(称牛痘)从手臂到手臂、从一个人身上转移到另一个人身上，问题是如何找到提供大量疫苗的方法，这个问题最终通过在牛胁腹部种植疫苗病毒的办法解决了。

The problem was to discover how to provide large amounts of vaccine. This was eventually solved by growing the vaccine virus on the flank of cows.

youdao