Allogeneic CMV-Specific CD19-CAR T Cells Plus CMV-MVA Triplex Vaccine After Matched Related Donor Hematopoietic Cell Transplant for the Treatment of Patients With High-Risk Acute Lymphoblastic Leukemia

Inclusion Criteria: * Documented informed consent of the participant and/or legally authorized representative * Assent, when appropriate, will be obtained per institutional guidelines * Agreement to allow the use of archival tissue from diagnostic tumor biopsies * If unavailable, exceptions may be granted with study PI approval * Note: For research participants who do not speak English, a short form consent may be used with a City of Hope (COH) certified interpreter/translator to proceed with screening and leukapheresis, while the request for a translated full consent is processed * Age: ≥ 18 years * Karnofsky performance status (KPS) ≥ 70 * Participants with high-risk ALL defined as: * Any complete remission (CR) with minimal residual disease (MRD)+ (by flow cytometry, polymerase chain reaction \[PCR\] or clonoSEQ) at the time of HSCT; or * Blasts ≥ 5% at the time of transplant; or * Complete response (CR)2 or higher irrespective of MRD status; or * Requiring \> 1 regimen to achieve CR1 * Pathology confirmed CD19+ ALL after the last targeted therapy if the patient has active disease or before the last therapy if the patient is in CR * Note: CD19 positivity must be documented in a pathology report; however, it is not a requirement that the CD19 testing be performed by a COH pathologist * Planned allogeneic HSCT (myeloablative or reduced intensity conditioning) according to institutional eligibility requirements with an available 8/8 (HLA A, B, C, DR) allele-matched related is allowed per discretion of the principal investigator. for allogeneic HSCT will be unmanipulated mobilized peripheral blood stem cell (PBSC) or bone marrow * Participants who received other prior forms of CAR T therapy are eligible * No known contraindications to HSCT, leukapheresis, steroids or tocilizum,ab, smallpox vaccine and any other modified vaccinia ankara virus (MVA)-based vaccines * Total serum bilirubin ≤ 2.0 mg/dL (to be performed no more than 45-days prior to hematopoeitic stem cell \[HSC\] infusion unless otherwise stated) * Participants with Gilbert syndrome may be included if their total bilirubin is ≤ 3.0 (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Aspartate aminotransferase (AST) \< 2.5 x upper limit of normal (ULN) (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Alanine aminotransferase \< 2.5 x ULN (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Serum creatinine ≤ 2.5 x ULN or estimated creatinine clearance of ≥ 40 mL/min per the Cockcroft-Gault formula, and the participant is not on hemodialysis (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Cardiac function (12 lead-electrocardiogram \[ECG\]): Corrected QT interval (QTc) must be ≤ 480 msec (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Left ventricular ejection fraction ≥ 45% within 8 weeks before protocol therapy (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Oxygen (O2) saturation \> 92% without requiring supplemental oxygen (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Seronegative for HIV quantitative real time polymerase chain reaction (qPCR), hepatitis C virus (HCV), active hepatitis B virus (HBV) (surface antigen negative), and syphilis (RPR) (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * If positive, hepatitis C ribonucleic acid (RNA) quantitation must be performed OR * If seropositive for HIV, HCV or HBV, nucleic acid quantitation must be performed. Viral load must be undetectable * Negative for COVID-19 within 72 hours of day 0 of protocol therapy (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Negative for human herpes virus-6 (HHV6) by PCR-based assay (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Meets other institutional and federal requirements for infectious disease titer requirements (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Participants must have negative QuantiFERON-TB Gold (QFTG) test (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * Participants with positive QFTG test need clearance from ID before protocol therapy * Women of childbearing potential (WOCBP): Negative urine or serum pregnancy test (to be performed no more than 45-days prior to HSC infusion unless otherwise stated) * If the urine test is positive or cannot be confirmed as negative, a serum pregnancy test will be required * Agreement by females and males of childbearing potential to use an effective method of birth control or abstain from heterosexual activity for the course of the study through at least 6 months after the last dose of protocol therapy * Childbearing potential defined as not being surgically sterilized (men and women) or have not been free from menses for \> 1 year (women only) * DONOR CRITERIA: The identified donor must be the original donor whose stem cells were used for the research participant's alloHSCT * DONOR CRITERIA: Donor must be CMV seropositive through the following: * CMV seropositive AND * CMV positive by CMV insight T cell immunity testing through Viracor (Test code 30360) * DONOR CRITERIA: The donor's hepatitis B surface antigen must be negative and the hepatitis C antibody must be nonreactive. In the case of a positive hepatitis C antibody result, the HCV viral PCR will have to be performed and the results should be negative * DONOR CRITERIA: The donor must be HIV negative * DONOR CRITERIA: KPS ≥ 70 * DONOR CRITERIA: Documented body weight * DONOR CRITERIA: Willingness to sign 'donor consent form' and undergo T cell leukapheresis for the collection of PBMCs for cellular manufacture * DONOR CRITERIA: COH standard opera