This literature report was received from a physician regarding a 12 year old male patient with pre-B cell acute lymphoblastic leukemia (ALL). The patient had received corticosteroids in previous 28 days. The patient had household contact with a live-in nanny with localized herpes zoster (shingles) on a lower extremity. Patient did not received post exposure varicella zoster immune globulin (VZIG). Serology varicella-zoster virus (VZV) immunoglobulin G, performed before administration of any blood product, was positive value, 182.2 index; positive, > 165 index; equivocal, 135-165 index; negative, <135 index) before initiation of chemotherapy. Nine months after diagnosis of ALL, varicella serology was repeated and was negative (Chemiluminescence Immunoassay value, 133.1 index). On unknown dates (at age 1 year and 7 year), the patient had received varicella virus vaccine live (Oka/Merck) (manufacturer unknown) for prophylaxis (dosing details were not reported). The patient was concomitantly taking 6-mercaptopurine, methotrexate, vincristine, and prednisone. On an unknown date, the patient was admitted to hospital with complaints of fever and a rash. On the night before his hospital admission, his mother noted a red papule on his right thigh. Over the next few hours, he developed 2 additional lesions with a similar appearance on his abdomen. Physical examination revealed a well appearing boy in no distress. His vital signs were notable for a temperature of 38.1 degree Celsius and pulse rate of 114 per minute. There were 3 vesicular lesions on an erythematous base, 1 on his right thigh and 2 on the abdomen. He had a central venous catheter in the left upper chest. The remainder of his physical examination was within normal limits. Within a few hours, additional lesions with a similar appearance developed on his abdomen and upper back. Initial laboratory evaluation revealed a white blood cell count of 3100 cells/microliter, with 80% segmented neutrophils, 2% band neutrophils, 8% lymphocytes, 5% monocytes, 4% eosinophils and 1% metamyelocytes. The hemoglobin was 14.9 grams per deciliter and platelet count was 132000 cells/microliter. Serum sodium was 131 mEq/L, AST and ALT were 451 and 805 units per liter, respectively, and total bilirubin was 2.3 milligrams per deciliter. Treatment with intravenous acyclovir was initiated at a dose of 30 mg/kg per day, and he received 1 dose of intravenous ceftriaxone. During the first 2 days of hospitalization, he had fever, chills, rigors, nausea, and anorexia. Multiple additional lesions that were pruritic appeared on his trunk, extremities, head, and scalp with a total of approximately 50 lesions. Hepatic transaminases peaked on hospital day 2 with AST of 647 units per liter and ALT of 913 units per liter and subsequently declined but remained above normal. Total bilirubin normalized on hospital day 3. He developed mild neutropenia (1300 cells/microliter) on hospital day 2, and intravenous antibiotics were re-initiated. His platelet count nadir was 96000 cells/flL on hospital day 4. After hospital day 4, there were no new lesions and the existing lesions began to crust. On hospital day 7, he received granulocyte colony-stimulating factor. He completed 7 days of intravenous acyclovir with clinical resolution of symptoms and signs. Fluid from a vesicle grew VZV in cell culture, and VZV deoxyribonucleic acid was detected using a polymerase chain reaction (PCR). By real-time PCR testing, the fluid was demonstrated to contain wild-type VZV. Infection occurred despite receipt of 2 doses of VARIVAX before diagnosis of ALL (vaccination failure). In addition, he had serologic evidence of immunity before initiation of chemotherapy. Either receipt of 2 doses of vaccine or serologic evidence of immunity fulfills criteria for evidence of immunity to varicella, yet he developed varicella. At the time of report, outcome of vaccination failure was not reported. The author assessed the causality for vaccination failure with VARIVAX as related. Additional information has been requested.