> rapidly test the efficacy of a vaccine How do you test the efficacy if you don't know who you're injecting? Maybe it works really well on a certain populatio

> rapidly test the efficacy of a vaccine How do you test the efficacy if you don't know who you're injecting? Maybe it works really well on a certain population, and reacts harmfully to people with some pre-existing genetic trait or condition. You wouldn't know, because you took a random set of volunteers. If you're going to counter and say "we'd still do the pre-analysis on the volunteers"... Well, that's what takes time.