Persistence of Anti-HBs Among Palestinian Medical Students After 18 - 22 Years of Vaccination: A Cross-Sectional Study

Background: Hepatitis B infection is a global public health problem affecting various sectors in the society. Vaccination is the first line measure to prevent the disease. Objectives: To assess the persistence of anti-HBs marker among medical students after 18 - 22 of vaccination as an indicator for Hepatitis B virus vaccine efficacy. Patients and Methods: In this study, 249 Palestinian medical students vaccinated at birth, 1, and 6 months of age using Engerix™-B starting from 1992 were studied. About 58% (144/249) of the students were Palestinians holding Israeli citizenship, while 42% (105/249) were Palestinians from the West Bank. Students were tested serologically for anti-HBs, as a marker for vaccine-induced immunity. Results: Over 75% (188/248) of students had levels of anti-HBs greater than 10 mIU/mL indicating immunity and protection. Five cases had positive results for anti-HBc indicating exposure to HBV infection; however, none of these cases showed any sign of HBV-DNA indicating effective clearance of the virus by the vaccine. Around 57% of the study group had anti-HBs level of 100 - 1000 mIU/mL. No significant association was found between anti-HBs level and age, sex, locality and level of anti-HBc (P > 0.05). The students were aware of different aspects of hepatitis B infection regarding the virus, symptoms, prevention and mode of transmission. Conclusions: The Palestinian and Israeli official policies to give a booster dose for risk groups like medical students at anti-HBs level below 10 mIU/mL should continue to ensure absolute protection. The currently-used vaccine and its time program cleared virus from students believed to have been exposed to the virus during their lifetime.