The Impact of Chemotherapy after Pediatric Malignancy on Humoral Immunity to Vaccine-Preventable Diseases.

Background/Aim: The antibody titer of vaccine-preventable diseases in pediatric patients who underwent chemotherapy was assessed in order to evaluate the seroprotection after treatment and the feasibility and the efficacy of a policy of revaccination. Methods: Serum antibody titers of 55 patients for hepatitis B (HBV), rubella, varicella-zoster (VZV), measles, mumps, polio viruses, Clostridium tetani (C. tetani) and Streptococcus pneumoniae (S. pneumoniae) were analysed. Results: After chemotherapy, a lack of protective antibody titers against HBV, rubella, VZV, measles, mumps, polio viruses, C. tetani, and S. pneumoniae was found in 53%, 45%, 46%, 46%, 43%, 21-26%, 88% and 55% of patients, respectively. In 49 of 55 patients who were tested both before and after chemotherapy for at least a pathogen, the loss of immunity for HBV, rubella, VZV, measles, mumps, polio viruses and C. tetani was respectively 39%, 43%, 38%, 42%, 32%, 33%, and 80%. A low number of B-lymphocytes was associated with the loss of immunity against measles (p=0.04) whereas a high number of CD8+ T-lymphocytes was associated with the loss of immunity against VZV (p=0.03). A single booster of vaccine dose resulted in a seroprotection for HBV, rubella, VZV, measles, mumps, polio viruses, C. tetani and S. pneumoniae in 67%, 83%, 80%, 67%, 33%, 100%, 88% and 67% of patients, respectively. Conclusions: We confirm that seroprotection for vaccine-preventable diseases is affected by treatment for pediatric malignancy. A single booster dose of vaccine might be a practical way to restore vaccine immunity in patients after chemotherapy.