Smallpox vaccination became common in the 19th century.

天花疫苗接种在19世纪普及开来。

Smallpox vaccination became common in the 19th century. During the American Civil War, all new soldiers on both sides were required to be vaccinated.

天花疫苗在19世纪开始普及。在美国南北战争期间，双方所有新兵都被要求接种疫苗。

For me, it was the literary equivalent of a smallpox vaccination: I have never, so far as I know, used the word zestful in a novel or a story. God willing, I never will.

对我来说，这就像注射了文学意义上的牛痘，终生对天花免疫：据我知道，我写短篇也好，长篇也罢，从来没有用过“热情的”这个词，总是尽力避免。