That's not right. We don't know if it does nothing, slows spread or stops it completely. We don't know yet, because it takes a long time to work that out.
Surely they tested it to find out before releasing it? So there's doubts about it's level of protection and whether it stops transmission or not. I see the urgency of the situation, but there just too many grey areas to be considering having this vaccine now and probably for a good while yet.