Some defend primarily against viruses, others work better against bacteria, parasites or fungi. To the body, a transplanted organ is probably more like a virus than a bacteria it is a normal cell that has weird things on its surface. That is why transplanted patients are very susceptible to viruses. To a lesser extent there is also some increased susceptibility to bacterial infections. Precautions against infection must be individualized for each patient.
Different patients are on different amounts of immunosuppression.
Different transplant centers have different immunosuppression systems. Different regions of the country can have different infection risks. Each patient must ask their own transplant team for their advice. The following comments apply to transplant patients in general. The more immunosuppression a patient has received the more precautions are necessary.