Investigation the Longevity of Hepatitis B Surface Antibody in Vaccinated Students of Hormozgan University of Medical Sciences

Background and objectives: hepatitis b is a common chronic viral infection in humans. universal use of hepatitis b vaccine is crucial for controlling the infection, but the duration of vaccine-induced immunity remains uncertain. this study aimed to assess hepatitis b antibody levels (anti-hbs) after vaccination in infancy and adolescence, and explore the relation- ship between immunity levels and variables such as age, sex, bmi, place of birth, and duration since last vaccination among students at hormozgan university of medical sciences from 2019 to 2021. materials and methods: the study included 1134 students who completed a questionnaire and provided blood samples for elisa-based measurement of antibody titers. results: the findings revealed that 727 students (64.1%) had no protective antibody level (anti-hbs <10 miu/ml), 299 (26.4%) had partial immunity (anti-hbs 10-100 miu/ml), and 108 (9.5%) had complete immunity (anti-hbs >100 miu/ml). no statistically significant relationships were observed between anti-hbs titer and age, sex, or bmi. however, antibody titer decreased with increasing time since last vaccination (p<0.001). conclusion: this study highlights the decline in antibody titer over time following primary vaccination. sustained immunity against hepatitis b virus relies on antibody durability or robust immunological memory, suggesting the importance of timing booster vaccinations.