Methodology:
This prospective observational study was carried out in the Department of Pediatric Oncology, of a Regional Cancer Centre, in India from 1st April 2018 to 31st March 2019 after obtaining institutional review board and Ethical Committee approval. All consecutive ALL children ≤14 years at diagnosis and receiving maintenance chemotherapy during the study period were included after obtaining written informed consent. Children with pre-existing primary or acquired immunodeficiency were excluded. Data regarding diagnosis, treatment, and infections requiring admission and inpatient care (severe infection) during maintenance phase were recorded. Total duration of maintenance chemotherapy was divided into four phases – 0 to 6 months, 7 to 12 months, 13 to 18 months and 19 to 24 months and period of maintenance at the time of recruitment was recorded. Serum immunoglobulin levels were measured by turbidimetric method using Vitros® kit (Ortho diagnostics) at recruitment and compared to age-matched reference ranges. All recruited children were followed up for development any severe infection for a period of 6 months from the date of recruitment, or till completion of maintenance treatment, or occurrence of any event or death due to any cause.