The vaccine was significantly more effective … if they had not b

来源: 于 2015-12-01 14:18:31 [博客] [旧帖] [给我悄悄话] 本文已被阅读：次

The vaccine was significantly more effective … if they had not been vaccinated in the previous five years.

这句话还不能说明问题吗？ 应该好好想想是不是要年年都打疫苗，或者应该每5年打一次？