Live vaccines are gradually replaced by protein-based vaccines given the latter's better safety. But live vaccines seem to be more efficient via stimulation of the innate immune system.

中文翻译：

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第二次来：活疫苗的卷土重来。

鉴于后者的安全性更好，活疫苗逐渐被基于蛋白质的疫苗所取代。但活疫苗似乎通过刺激先天免疫系统更有效。