The purpose of a vaccine is to train your immune system to prevent the replication of said virus that enters your body. If a vaccine provokes the right immune response, you will be protected entirely against the virus unless there are multiple mutations that render the antibodies useless. There is no way to pass on a virus to someone else when you are protected entirely from a virus. So, currently, unless further evidence suggests that the virus is mutating and the vaccine will be ineffective against Covid-19, vaccinated persons cannot pass it on to others. In the event that the vaccine does not provoke an appropriate immune response, they can still pass it on. However, the efficacy of the vaccine is 90-95%, so it extremely unlikely that’s the case. An effective immune response and the inability to spread the virus go hand in hand.