Response to Influenza Vaccination in Pediatric Oncology Patients

Influenza infection occurring during oncologic treatment or following hematopoietic cell transplantation (HCT) is associated with increased risk of morbidity in the form of lower respiratory tract infection (LRTI) and mortality relative to otherwise healthy patients. The study participants have been diagnosed with a hematological malignancy and are eligible to receive the current seasonal influenza (Flu) vaccine. Primary Objective * To determine the feasibility of opening a longitudinal prospective study of IIV immunogenicity in pediatric leukemia patients. * To describe the immunogenicity, as measured by the development of cell- and/or antibody-mediated influenza specific responses 3 to 5 weeks following vaccination, in a cohort of pediatric leukemia patients. Secondary Objectives * To describe whether an immune response, as measured by development of cell- and/or antibody-mediated influenza specific responses, is detectable 1-2 weeks following vaccination in a cohort of pediatric leukemia patients. * To describe the durability of immunogenicity by measuring cell - and antibody- mediated influenza specific responses at 6 months and 1 year following vaccination in a cohort of pediatric leukemia patients. Exploratory Objectives * To estimate the clinical effectiveness of influenza vaccine in this cohort by monitoring for the development of clinical diagnosis of influenza in the cohort of enrolled pediatric oncology patients. * To correlate results of immune cell frequency in blood, as measured by complete blood count with differential, with development of an immune response to IIV.