Vaccine-Induced Immunity in Children and Adolescents After Chemotherapy for Acute Lymphoblastic Leukemia: A Systematic Review.

BACKGROUND

Acute lymphoblastic leukemia is the most prevalent childhood cancer and the leading cause of cancer mortality before the age of 20. Although therapeutic advances have significantly improved survival, children and adolescents treated for acute lymphoblastic leukemia remain vulnerable to infections, largely preventable by vaccination, due to humoral and cellular immune dysfunction induced by disease and treatment.

MATERIALS AND

METHODS

This systematic review, based on electronic databases, aims to evaluate antibody levels associated with potential protective immunity against vaccine antigens for diphtheria, pertussis, tetanus, poliomyelitis, Haemophilus influenzae type b, measles, mumps, rubella, influenza, varicella-zoster virus, yellow fever, pneumococcal, and meningococcal diseases in children and adolescents treated for acute lymphoblastic leukemia after completion of chemotherapy.

RESULTS

A total of twenty-four studies published between 1981 and 2023 were included, comprising 1110 children and adolescents. Protective antibody levels ranged from 11% to 97% for diphtheria, 0% to 90% for pertussis, 20% to 100% for tetanus, and 11% to 95% for poliomyelitis. Haemophilus influenzae type b, protection ranged from 16.7% to 100%. Viral vaccines also showed heterogeneous responses, with protection rates of 25-79% for mumps, 16-86% for measles, 35-98% for rubella, and 23-75% for varicella-zoster virus. Antibody responses to pneumococcal and meningococcal vaccines were consistently low, with protection rates of 5-38% for pneumococcal studies and 12% in a single meningococcal study.

CONCLUSIONS

This review found a consistent and clinically relevant loss of vaccine-induced immunity in children and adolescents treated for acute lymphoblastic leukemia. The recommendation of vaccine booster doses for this vulnerable population, irrespective of serological status, may represent a more practical approach to ensuring adequate post-chemotherapy treatment protection.