There is a great deal of research in progress on maximizing protection of transplant recipients against Covid 19 and its variants. A recent study from Johns Hopkins among a small group of recipients found that the effectiveness of the vaccines continues to lag from that experienced by the general population.
A great deal of research is being conducted using third and even fourth doses of the vaccines--more information and guidance is expected shortly. In the meantime, transplant recipients continue to be urged to continue with the safe social practices that have been necessary since the beginning of the pandemic: maintaining social distancing, wearing masks, maintaining personal hygiene, and being aware of surroundings.
The Johns Hopkins study can be found here.