Longitudinal Analysis of Antibody Response to Immunization in Pediatric Survivors After Allogeneic Hematopoietic Stem Cell Transplantation.

Abstract 795

Re-immunization is a common practice after allogeneic hematopoietic stem cell transplantation (allo-HSCT), but the optimal vaccine schedule and long-term response have not been established. We prospectively and longitudinally evaluated the antibody response to childhood vaccines in 210 survivors after allo-HSCT. Positive titer lasting for 5 years or more after immunization was observed more often for diphtheria (98.1%), tetanus (96.1%), rubella (92.9%), and polio vaccines (96.2% for type 1; 98.1% for type 2 and 3), but less often for pertussis (25.0%), measles (65.4%), mumps (64.3%), and hepatitis B (75.0%). As shown in the table below, vaccine failure was associated with patients who were older at the time of re-immunization, received a T cell depleted graft, had a high-risk hematological malignancy, lower IgG levels, higher IgM levels, chronic GvHD, positive recipient CMV status, and negative titers prior to immunization. These clinical factors are useful to formulate immunization and monitoring strategies for survivors after allo-HSCT. Patients at risk for vaccine failure should be monitored closely during long-term follow-up, and booster immunizations should be considered when there is no seroconversion.