There's been a few people commenting here that it helps reduce the R rate, or that vaccine will help reduce transmission etc. Nope. There's no evidence yet that that happens. What they are testing for with the vaccines is that people don't suffer any effects of the virus, but vaccinated people are still capable of receiving and transmitting the virus.
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31976-0/fulltext
https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(20)31976-0/fulltext