Decrease in Anti-HBs Antibodies over Time in Medical Students and Healthcare Workers after Hepatitis B Vaccination

BACKGROUND Hepatitis B is one of the most important occupational hazards among healthcare workers (HCWs). This study aimed to measure the anti-HBs titres among the medical students and HCWs vaccinated against hepatitis B virus and to determine the association between anti-HBs levels and time since vaccination. MATERIALS AND METHODS In this cross-sectional study, medical students and healthcare workers who had received all three doses of hepatitis B vaccination and completed at least six months after vaccination since the last dose were included. 3 ml blood was collected from subjects (n = 340) and anti-HBs titre was estimated using ELISA. RESULTS A total of 340/400 subjects were aged between 18 and 60 years; 204 were females and 136 males. The median and interquartile range for time since vaccination were 5 and 5 years, respectively. Duration since vaccination was ≤5 years in 223 (65.5%), 6-10 years in 84 (24.7%), and >10 years in 33 (9.70%); among them, antibody titres were >10 mIU/ml in 94.1%, 79.7%, and 72.7% subjects, respectively. There was significant decline in antibody titres as duration of postvaccination increased. CONCLUSION The proportion of subjects who were unprotected after 5 and 10 years after vaccination were 20% and 27%, respectively. The need for a booster dose can be made mandatory at least for healthcare professionals.