今天，我们要讨论的话题是疫苗，以及注射疫苗的重要性。

Our bodies have an immune system that protects us from infections and diseases.

身体免疫系统可防止感染和疾病。

Basically, a vaccine helps get our immune system ready to fight off a certain illness.

基本上，疫苗可帮助免疫系统对抗特定疾病。

A vaccine is usually made of the germ that could make you sick, but the germ is weakened or killed.

通常，疫苗含有许多致病细菌，但这些细菌已无法致病或已经死亡。

When a vaccine enters our body, the immune system thinks it’s the real germ and responds to it the same way it does to germs, it fights it.

当疫苗进入体内，免疫系统认为它是细菌，并将以对抗细菌的方式对抗疫苗。

But, the vaccine is easier to fight than the illness you’re being vaccinated against, and it won’t make you sick.

然而，这种疫苗比对抗疾病来说更加容易，且不会致病。

Once the immune system figures out how to fight a germ and win, it remembers what works.

一旦免疫系统战胜该疫苗，它将会依循原有记忆进行保护。

Should such an enemy enter your body again, your immune system is ready to fight it off and will move to attack before it has a chance to make you sick.

一旦敌人再次侵入身体，免疫系统将在致病之前消灭敌人。

Sometimes our immune systems need a refresher course, which is why we get booster doses of some vaccines.

免疫系统有时也需要提神，这就是为什么我们要注射加强针的原因。

Some germs are tricky and change over time, like flu viruses.

像流感等病毒随时都在发生变化。

We need to get the flu vaccine every year so our bodies can be ready to take on the latest flu viruses!

我们每年都需注射流感疫苗，保证免疫系统可对抗最新流感病毒。

1.need to 需要

例句：You need to touch up the poem.

你需要给这首诗润色一下。

2.immune system 免疫系统

例句：So if you take them away, the immune system runs wild, as it has nothing to work against.

所以如果你清除了他们，免疫系统运转就会失控，因为它失去了与之抗衡的力量。

3.be ready to 为…做准备

例句：So if you come, be ready to dance.

因此，如果你来到这儿，就准备好起舞吧。

4.vaccinate against 给..接种疫苗

例句：The children were all vaccinated against smallpox.

所有儿童都种了牛痘以预防天花。