A Multi-site Study to Evaluate the Persistence of Protective Immunity to Routine Childhood Vaccinations in Participants With B-ALL/Ly Who Have Received Blinatumomab

The goal of this observational study is to establish a clear vaccination protocol for pediatric patients (less than 21 years old) who have received treatment for B-cell Acute Lymphoblastic Leukemia/Lymphoma. The main study aims are: * Evaluate the persistence of protective immunity to routine childhood vaccinations in participants with B-ALL/Ly who have received blinatumomab. * To determine whether revaccination in participants with non-protective titers leads to restored humoral immunity. Researchers will compare results from participants who have received immunotherapy to those who have not received immunotherapy to see if immunotherapy versus other chemotherapeutic drugs adversely affect the protective immunity acquired through vaccination.