Immune Function and Response to Vaccination After Cancer Therapy in Pediatric Patients

This study is a prospective, randomized trial. The target population is all patients between the ages of 2 and 21 years of age who complete cancer directed systemic therapy for any malignant diagnosis at our center over a 2 to 3-year time frame. The study will be conducted in the various disease-specific off therapy and survivorship clinics of Levine Children's Cancer and Blood Disorders. Patients will have lab evaluations for immune function at baseline, 3, 6, 12, and 24 months from last dose of cancer directed systemic therapy. At 3 months from last dose of cancer directed systemic therapy, patients with abnormal vaccine antibody titers will be randomized to receive either single booster vaccines or to begin a full revaccination series that models post-hematopoietic stem cell transplant vaccination strategies. Vaccines given will be directed against Haemophilus influenza type B, tetanus, diphtheria, pertussis, polio, hepatitis B, Streptococcus pneumoniae, measles, mumps, rubella, and varicella. Live vaccines (measles, mumps, rubella, and varicella) will be given at 6 months from last dose of cancer directed systemic therapy. Repeat vaccine antibody titers will be assessed at follow up visits as above to determine if there are differences in immediate or maintained immunity based on vaccine strategy used. For subjects \<18 years of age, we will present health questionnaires to their caregiver to answer at each of the time points. Subjects ≥18 years of age will complete their own health questionnaire. These questionnaires will assess frequency, type, and severity of viral and bacterial infections requiring antibiotics in study patients and their closest healthy sibling in age, when applicable.