它们可以产生足够多的新病毒来训练免疫系统杀死并记住它们，所以人们只需要接种一次疫苗。

They can produce enough new viruses to train the immune system to kill and remember them, so people only need to take the vaccine once.

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世卫组织在该领域的工作包括制定标准、加强免疫系统、管理疫苗质量和供应、资助以及研究与开发。

WHO's work in this area includes setting standards, strengthening immunization system, regulating vaccine quality and supply, finance, and research and development.

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HIV研究人员希望利用某种物质(通常是病毒自身的一部分)研制出疫苗，刺激免疫系统释放抵抗病毒的抗体。

HIV researchers hope to make a vaccine from a substance — usually a piece of the virus itself — that will provoke the immune system into releasing virus-fighting antibodies.

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They did this very systematically, by giving quantities of the vaccine to countries all over the world.

他们做了系统的工作,把大量天花疫苗送到世界各地

耶鲁公开课 - 生物医学工程探索课程节选

And that person who really studied it systematically, and is given credit for developing the first vaccine, is a Scottish physician named Edward Jenner.

而那个系统研究疫苗,并被誉为发明了第一支疫苗的人,叫爱德华?詹纳,是苏格兰的一名医生

耶鲁公开课 - 生物医学工程探索课程节选

So, what that really means, you know, from last week's lecture, is that the vaccine stimulates these particular cells in your immune system to give you immunity.

所以,这就意味着,通过上周的课程,你们知道,疫苗通过刺激免疫系统中的,特定细胞来使人获得免疫力

耶鲁公开课 - 生物医学工程探索课程节选