People can't afford them. That's why we don't really have a malaria vaccine yet, because no one in rich countries really suffers from malaria.

VOA: special.2010.03.29

Children get diseases from a class of viruses called rotaviruses, for which we have no vaccine, and- and so no way to protect them.

儿童因轮状病毒而生病,而我们没有针对这种病毒的疫苗,所以,所以我们没有办法保护儿童

耶鲁公开课 - 生物医学工程探索课程节选

There's no company that's making smallpox vaccine anymore because there's no reason to make smallpox vaccine, because nobody would buy it, right?

没有公司还生产天花疫苗,因为没有人购买天花疫苗,因此早就没有理由继续生产它了,对吧

耶鲁公开课 - 生物医学工程探索课程节选

But there was no plan for distributing a pandemic level vaccine in the U.S.or anywhere.

VOA: standard.2010.04.29

The Obama administration says it is laying the groundwork to develop a vaccine against swine flu, although no decision has been made on large-scale production of such a vaccine.

VOA: standard.2009.05.03