记得去年就有关于疫苗的不好的新闻。
今年又来了。
气到不知道说什么好。
发一个关于疫苗的段子，故事都是我们知道的，关于天花

再发几个关于疫苗起作用原理的段子x
why did it work?
要明白为什么，就要首先了解免疫系统
To understand how vaccines function, we need to know how the immune system defends us against contagious diseases in the first place.
免疫系统能够识别并将外源的微生物移除
When foreign microbes invade us, the immune system triggers a series of responses in an attempt to identify and remove them from our bodies.
免疫反应的外在表现有咳嗽打喷嚏炎症还有发烧。
The signs that this immune response is working are the coughing, sneezing, inflammation and fever we experience.
上述是先天免疫。发生较快。

先天免疫能够激发后天免疫
These innate immune responses also trigger our second line of defense, called adaptive immunity.
B和T细胞可以记忆这些外来入侵物
Special cells called B cells and T cells are recruited to fight microbes, and also record information about them, creating a memory of what the invaders look like, and how best to fight them.
This know-how becomes handy if the same pathogen invades the body again.

免疫需要时间，而且体弱和年幼的人，可能再次感染时依然无法抵抗
The body takes time to learn how to respond to pathogens, and to build up these defenses.
And even then, if a body is too weak or young to fight back when it's invaded,
it might face very serious risk if the pathogen is particularly severe.

疫苗在这时就凸显了作用
This is where vaccines come in.

Using the same principles that the body uses to defend itself, scientists use vaccines to trigger the body's adaptive immune system, without exposing humans to the full strength disease.

下面一段讲了不同类型的疫苗
有减毒疫苗attenuate vaccine
灭活疫苗inactive vaccine
这两种疫苗为传统疫苗
新型疫苗有
亚单位疫苗subunit vaccine
核酸疫苗DNA vaccines
等