Originally Posted by MoAlpha

That’s a natural question and this stuff is not very intuitive. The “endpoint” of the trials which led to the Emergency Use Authorization of the vaccines was prevention of clinical disease. That’s the lowest bar for a vaccine to clear. It would have also been a huge undertaking to do repeated testing of such huge study groups and they didn’t do it. Therefore, the question of whether the vaccines prevent infection, per se, has had to wait for studies like this. One thing I’ve learned recently is that many effective vaccines actually don’t.