<qa>  What is the purpose of the study?Patients who receive transplants are at increased risk of developing serious cytomegalovirus CMV infections because they have a decreased immune system. The purpose of this study is to evaluate the safety and immune response of a CMV vaccine in patients 18 years old and older who are awaiting a transplant. Following immunization with vaccine or placebo inactive substance, patients will be followed for the development of immune responses to CMV and for evidence of CMV infection following transplantation. One hundred forty eligible patients will receive 3 injections of the CMV gB vaccine or 3 doses of placebo during 5 visits. Participants will participate in the study for approximately 7 months if they do not undergo a transplant or 10 months if they undergo a transplant. 