Abstract
BACKGROUND: Hepatitis B virus (HBV) infection remains a significant occupational health concern for healthcare workers (HCWs), including trainees exposed to biological risks. Although vaccination is the most effective preventive measure, the persistence of immunity over time and the need for booster doses remain subjects of debate. OBJECTIVE: The present study aims to assess the prevalence of protective anti-HB antibody titers among healthcare trainees at the "SS Annunziata" Hospital in Chieti, comparing those vaccinated in infancy with those vaccinated during adolescence. METHODS: A retrospective observational study was conducted on 2028 healthcare trainees from 2021 to 2024. Participants were divided into two groups based on vaccination timing: infancy (PED group) and adolescence (ADO group). Serological tests were performed to measure anti-HB titers, with a protective threshold set at ≥10 IU/L. Statistical analyses were conducted to evaluate differences in immunity persistence between the two groups. The results showed that the overall prevalence of protective anti-HB titers was 50.7%, with significant differences between the PED and ADO groups. Protective immunity was observed in 79.2% of individuals vaccinated during adolescence, compared to 44.6% of those vaccinated in infancy (p < 0.001). No significant differences in antibody persistence were found between males and females. Notably, 92.4% of participants with non-protective titers received a booster dose within two months of testing. CONCLUSIONS: The study confirms a significant decline in anti-HB titers over time among individuals vaccinated in infancy, suggesting a potential need for booster doses later in adulthood. The high adherence to vaccination recommendations among healthcare trainees is a promising finding, reinforcing the importance of continuous education and immunization programmes in healthcare settings. Further research, including longitudinal studies and additional HBV biomarkers, is necessary to optimize vaccination strategies and long-term immunity monitoring in HCWs.