It still helps the at risk people to take it asap as you won't be a carrier, doesn't it?
My complete layman understanding would be that it should at least somewhat prevent the spreading because replication has to be limited if a vaccine works and replication is also an important part of giving the disease to others? If less cells are infected you can't cough out the virus as much? But the exact timeline is important here, obviously. Again, complete layman, I know basically nothing about this.