Abstract / Summary
Abstract Objective: To evaluate serum tetanus IgG antibody levels in childhood cancer survivors (CCSs), investigate longitudinal dynamics pre- and post- chemotherapy, and determine the necessity of post-chemotherapy revaccination with tetanus-toxoid-containing vaccines (TTCVs). This aims to establish evidence-based guidelines for developing revaccination protocols in this vulnerable population. Methods: This cohort study enrolled CCSs (<15 years) hospitalized pre-chemotherapy at the Children's Hospital Affiliated to Zhejiang University School of Medicine between January 2022 and January 2023. Serial blood samples were collected at three critical timepoints: pre-chemotherapy baseline, and 1-month and 6-month post-chemotherapy intervals for the case group, alongside age-matched healthy controls recruited from community populations. Quantitative determination of tetanus-specific IgG antibodies utilized a standardized enzyme-linked immunosorbent assay (ELISA) (Verenserun kit V108.17). Results: The study included 379 CCSs and 379 healthy controls. Post-chemotherapy analysis unveiled a marked decline in tetanus IgG seropositivity compared to pre-treatment levels (70.45% vs 81.00%; χ²=93.66, P <0.001), with rates strikingly lower than healthy controls (82.69%; χ²=15.54, P <0.001). Geometric mean concentrations (GMC) demonstrated parallel reductions (0.73 ± 0.10 IU/mL post-chemotherapy vs 1.15 ± 0.16 IU/mL baseline, t=5.00, P <0.001; healthy controls: 1.10 ± 0.06 IU/mL, t=3.09, P =0.002),which was non-significantly different between CCSs pre-chemotherapy and healthy controls(t=-0.33, P =0.745). Longitudinal assessment at the 6-month follow-up (n=88) identified persistent seronegativity in 69.32% (61/88) of cases. Among 6 revaccinated patients receiving TTCVs, 66.67% (4/6) achieved seroconversion. Conclusion: Chemotherapeutic regimens significantly deplete tetanus IgG antibodies in CCSs, driving post-treatment titers below the World Health Organization (WHO) defined protective threshold (0.1 IU/mL). This serological evidence confirms treatment-induced erosion of pre-existing immune memory. Our data strongly advocate for structured revaccination protocols with TTCVs, initiated as soon as feasible under professional guidance following confirmed disease remission and immune function reconstitution. Such targeted immunological rehabilitation strategies are vital to restore protective immunity and mitigate tetanus-associated morbidity within this high-risk group.