The first step uses a bit of influenza DNA to get the patient's immune system to begin fighting off the flu, and then the protection is given a "boost" some time later by the second step, which can be either another bit of DNA or a conventional flu vaccine.

VOA: standard.2010.07.21

Now, if I was a person that was designing a vaccine and I noticed that this was the response that it got, that antibodies were produced, they reached some intermediate level, they started to fall, I would say, "Well I haven't stimulated the immune system enough, let me re-boost, let me give another dose of antigen."

现在,如果我正在研究一种疫苗,我注意到机体会对这种疫苗产生应答,也就是会产生抗体,当抗体浓度达到中等水平后,就开始下降,就可以说,疫苗对免疫系统刺激还不足,我需要提高抗原浓度,让我再把剂量再加大一倍

耶鲁公开课 - 生物医学工程探索课程节选

Now, if I was a person that was designing a vaccine and I noticed that this was the response that it got, that antibodies were produced, they reached some intermediate level, they started to fall, I would say, "Well I haven't stimulated the immune system enough, let me re-boost, let me give another dose of antigen."

现在,如果我正在研究一种疫苗,我注意到机体会对这种疫苗产生应答,也就是会产生抗体,当抗体浓度达到中等水平后,就开始下降,就可以说,疫苗对免疫系统刺激还不足,我需要提高抗原浓度,让我再把剂量再加大一倍

耶鲁公开课 - 生物医学工程探索课程节选