Riding In Cars With Researchers

Pfizer and BioNTech have just gotten a FDA EUA (Emergency Use Authorization). They also got EUA in England, and I believe in Canada at this point in time. We're expecting Moderna to get its’ EUA shortly, and there will be more to come.  What I don't want to see is people thinking that that's it, that's the end, that there's no more need to enroll in COVID vaccine research trials. Now, why would I argue that there is still a need?