- Subjects must have a platelet count of >= 30,000 to receive the immunizations; patients requiring platelet transfusions are eligible to enroll and must have a platelet count >= 30,000 within 72 hours prior to their immunization; for subjects < 12 months post-transplant, if a platelet count of >= 75,000 is documented without transfusion support within 14 days of the immunization, then an additional platelet count does not need to be repeated prior to immunization; for subjects 12-23 months post-transplant, if a platelet count of >= 75,000 is documented without transfusion support within 90 days of the immunization, then an additional platelet count does not need to be repeated prior to immunization