Assessment of Antibody Levels and Vaccine-induced Serologic Responses After Completion of Cancer Treatment in Pediatric Patients: A 6-Year Experience in Turkey on HAV, HBV, VZV, and MMR Vaccinations.

OBJECTIVE

Childhood cancer treatment disrupts vaccination schedules and weakens or eliminates vaccine-induced immunity. In addition, post-treatment vaccine responses vary. This study aimed to assess post-treatment serum antibody levels and vaccine responses in children.

METHODS

Pediatric patients treated at Hacettepe University between years 2015 and 2020, achieved remission after chemotherapy for lymphoma and solid tumors were included. Post-treatment vaccination status, serum antibody levels for hepatitis A (HAV), hepatitis B (HBV), varicella-zoster (VZV), measles-mumps-rubella (MMR), and changes in vaccine responses were retrospectively analyzed.

RESULTS

The study included 533 patients. Post-treatment seronegativity rates were: measles (83.5%), HAV (64%), rubella (60.1%), HBV (48.5%), VZV (43.3%), and mumps (28%). Post-treatment antibody loss was observed for measles (47.1%), HAV (31.9%), HBV (31.4%), mumps (28.6%), VZV (21.7%), and rubella (11.4%). Seropositivity after 1 vaccine dose was seen with HAV (83.6%), rubella (82.9%), HBV (81.4%), VZV (63.5%), mumps (45.4%), and measles (33.3%). Seropositivity after 2 vaccine doses was achieved with HAV (98.8%), VZV (84.6%), rubella (80%), HBV (80%), measles (32.2%), and mumps (36.2%).

CONCLUSION

Post-treatment serological vaccine responses in children were lower than anticipated despite multiple doses. Given the potential need for periodic serological assessments and booster vaccinations, long-term follow-ups are planned.