ABSTRACT
Haematopoietic stem cell transplantation [HSCT] is being used with increasing frequency as treatment option for various high risk malignant and non-malignant disorders. Myeloablative conditioning regimens given to eradicate malignant cell and to suppress the host immune system to avoid rejection results in dysfunctional immunity that persists for up to one year or longer. During this period, patients are at increased risk of infections representing major source of morbidity and mortality. The immune manipulation often required to manage graft rejection and graft versus host disease [GVHD] further delays immune reconstitution. This vulnerable period is also characterized by loss of immune memory to infectious agents and vaccines that the patients were exposed previously. Guidelines for immunization in post stem cell transplant patients is not clearly defined and there is no standard protocol exist for them moreover developments of new vaccines that utilize different immune mechanisms suggest that reappraisal of the immunization practices after HSCT is needed. So we think this appraisal will help making unified protocol for immunization in transplant patients