A vaccine is a biological preparation that improves immunity to a particular disease.疫苗是一种生物制备，用于提高身体对某种疾病的免疫力。vaccine ['væksi:n]：疫苗
preparation: 制备；特别配制成的药物
immunity [i'mju:nəti] ：免疫力
Traditional vaccines contain microbes that have been killed or weakened so that they don't cause disease.传统疫苗包含了病原菌，这些病菌已被灭活或人工减毒，不具备引发疾病的能力。The administration of vaccines is called vaccination.接种疫苗的过程叫做vaccination [,væksi'neiʃən]。When an individual is vaccinated against a disease or an infection his or her immune system is prepared to fight the infection.当一个人接种了某种疾病或传染病的疫苗，其免疫系统就做好了抵抗这种病的准备。vaccinate ['væksineit]：动词，接种疫苗
immune system：免疫系统
When a person is inoculated with these preparations, the immune system confronts these harmless versions of the germs. The immune system quickly clears them from the body.当一个人接种了这种制备，免疫系统就接触到了这些无伤害力的病菌。免疫系统会立刻把它们从体内清除。inoculated [i'nɔkjuleit]：接种
In turn the body remembers the germs so that later in life when it encounters the real live virulent germs it may be able to fight it off with the retained memory against the particular germ.然后身体就记住了这些病菌，将来在遇到真正有毒的病原菌时，就会依循其原有的记忆，来抵抗消灭病原菌。Before vaccines, the only way to become immune to a disease was to actually get it and, with luck, survive it.在有疫苗之前，人们能够对某种疾病免疫的唯一方法就是真正得一场病，并且如果幸运的话，活下来。
好了，现在我们归纳一下，英文“疫苗”怎么说？
vaccine /ˈvæk.siːn/ 疫苗
inject vaccine 接种疫苗
influenza vaccine 流感疫苗
polio vaccine 小儿麻痹疫苗
chickenpox vaccine 水痘疫苗
