[Immunization of adult hematopoietic stem cell transplant recipients: current recommendations and clinical...

Following hematopoietic stem cell transplantation (HSCT), most pre-existing immunity is significantly reduced or lost, necessitating comprehensive revaccination as recommended by established guidelines. Immune reconstitution post-HSCT is a prolonged process that typically requires at least 1 to 2 years, and is influenced by various factors including patient age, transplant type, and graft-versus-host disease. Although vaccine immunogenicity is often suboptimal in the early post-transplant period due to marked immunosuppression, this phase is also the period of greatest vulnerability to infection. Consequently, determining the optimal timing for post-transplant vaccination remains a subject of ongoing expert debate. In recent years, several new vaccines have been introduced in Japan, including recombinant zoster, higher-valent pneumococcal conjugate, and high-dose influenza vaccines. This review outlines the fundamental principles of vaccination following HSCT and addresses specific considerations for vaccine-preventable diseases based on current evidence and vaccine availability.