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

This study checks whether children and young adults who had a type of blood cancer called B-cell acute lymphoblastic leukemia (B-ALL) and were treated with a drug called blinatumomab still have protective immunity from their childhood vaccinations — or whether their immune response to those vaccines was wiped out by treatment. **You may be eligible if...** - You have a diagnosis of B-lineage acute lymphoblastic leukemia or lymphoma - You are up to 21 years old at diagnosis - You received all routine vaccinations given during your first year of life - Informed consent (and child assent, if applicable) was provided **You may NOT be eligible if...** - Your cancer relapsed or became refractory at any time - You received or will require a bone marrow transplant Talk to your doctor to see if this trial is right for you.