Abstract:
Background: In Algeria, Hepatitis B vaccination was integrated into the Expanded Program on Immunization (EPI) in 2000. Evaluating the long-term effectiveness and post-vaccination immune response in pediatric cohorts is critical to validate national immunization strategies, identify high-risk non-responders, and guide targeted clinical or preventive interventions.
Materials and Methods: This retrospective, cross-sectional study evaluated a representative cohort of 551 randomly recruited, fully vaccinated children in the Constantine region over a three-year period starting January 1, 2022. Anti-HBs antibodies were quantified at the Microbiology Department of the Constantine University Hospital Center (CHUC) using a high-sensitivity enzyme-linked immunosorbent assay (ELISA). A seroprotection threshold of >=10 IU/L was applied in accordance with WHO standards. Clinical, neonatal, and biological factors were extracted from medical files, and predictive variables for vaccine non-response were analyzed using SPSS (Chi-squared and Fisher's exact tests; significance threshold set at p < 0.05).
Results: The overall pediatric seroprotection rate was robust at 89.84% (495/551 children), with 57.35% exhibiting strong immunization (>100 IU/L) and 32.49% moderate immunization (10-100 IU/L). However, a physiological decay in anti-HBs titers was observed with age and time since vaccination, with the seroprotection rate declining from 95.92% at 2 years of age to 75.61% at 15 years (p = 0.004). Bivariate statistical analysis revealed highly significant predictors of vaccine non-response (anti-HBs < 10 IU/L): maternal HBsAg positivity (72.73% non-response, p < 0.001); low birth weight (<2000 g, 70.59% non-response, p < 0.001) and macrosomia (>4000 g, 87.5% non-response, p < 0.001); non-compliance with the vaccination schedule (63.1% non-response in irregular schedules, p < 0.001); type 1 diabetes (88.24% non-response, p < 0.001); and biological anemia (66.67% non-response, p < 0.001). No significant influence was found for gender (p = 0.064) or breastfeeding type (p = 0.258).
Conclusion: While the Algerian EPI provides robust overall pediatric coverage, the high non-response rate among children exposed to vertical transmission underscores the urgent need for systematic prenatal screening of pregnant women and standardized immunoprophylaxis (vaccine + HBIG) administered within 24 hours of birth. Personalized clinical vaccination protocols are essential for children with metabolic or hematological comorbidities (such as type 1 diabetes and anemia) and those with birth weight abnormalities to ensure durable protective immunity.
Keywords: Hepatitis B, Vaccination, Seroprotection, Children, Anti-HBs, Constantine, Algeria
Biography:
Dr. Loubna Bechir is a medical microbiologist and researcher at the Department of Microbiology, Constantine University Hospital Center (CHUC), and a faculty member at the Faculty of Medicine, University of Constantine, Algeria. Her research focuses on viral hepatitis, pediatric immunization efficacy, and public health microbiology. She has been actively involved in evaluating the Algerian Expanded Program on Immunization (EPI) and monitoring vaccine seroprotection rates to inform national prevention strategies and clinical guidelines for vulnerable cohorts.
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