时差N小时 疫苗的神奇作用(下)（在线收听）

The second type of vaccine contains an attenuated virus.

第二种类型的疫苗包含一种减毒病毒。

This virus is alive, but has been grown in the lab for several generations, so it isn't able to multiply very well in humans.

这种病毒本身是活的,但在实验室中已成长了几代,所以无法在人体中很好繁殖。

With the attenuated virus multiplying very slowly,your body is able to produce the correct antibodies before you get sick.

由于减毒病毒繁殖慢,因此你的身体在患病前就能够产生正确的抗体。

Measles and mumps vaccines are both made with attenuated viruses.

麻疹,腮腺炎疫苗都是用减毒病毒疫苗。

When most people in a community have become resistant to the virus, either through a vaccination or by having the virus and recovering, the community develops what is called “herd immunity”.

经过接种疫苗或感染病毒恢复，一个社区的大多数人已对病毒变得具有抵抗力,社区就会发展成为“群体免疫”。

The nice thing about herd immunity is that it becomes statistically less likely for the germ to find a person without immunity.

群体免疫的好处是,从统计角度病菌不太可能找到一个没有免疫力的人。

This protects members of the community who haven't been vaccinated, or had the disease, by reducing their chances of encountering an infected person.

这样通过减少接触感染者，社区未接种疫苗或有疾病史的人就会得到保护。