Thanks for your comment. I think it's clear in the text that phase III trials aren't enough because they have strict inclusion and criteria, which is why we have phase IV surveillance studies to see how the vaccines work in the real world. So, in a sense, it isn't enough for determining how the vaccines truly work in the real world.

That said, I have made some minor edits to clarify that Covid-19 risks are much greater where I think is appropriate. Thanks again for pointing this out.