Background: Hepatitis B virus is one of the main factors causing acute and chronic hepatitis and hepatocellular carcinoma. Among others, healthcare workers are at the highest risk for exposure to hepatitis B virus. Vaccination against hepatitis B virus is one of the protective strategies but anti-HBs titer will be reduced in the sera of vaccinated people after some time. The aim of this study was to determine the titer of anti-HBs in the sera of vaccinated medical staffs in three consecutive years since administration of the last dose of hepatitis B vaccine.

Materials and Methods: This study was carried out on 90 Omidvar Hospital (Lar, Iran) medical staffs that had passed 3-4 months since the administration of the last dose of hepatitis B vaccine. All sera samples were tested for anti-HBs in an ELISA method. Finally, statistical analysis was performed using SPSS-16 software.

Results: This study was conducted in duration of 3 consecutive years on 90 medical staffs including 14.44% lab technicians, 10% obstetricians, 43.35% nurses, 6.665% specialists, 5.55% general practitioners and 20% maid staffs. While HBs Ab titer was measured as 87.7% (>100 mIU/ml) in the first year elapsed since the last dose of hepatitis B vaccination, it had been decreased to 55.4% after 3 years.

Conclusion: The results showed that re-vaccination of the medical staffs is quite necessary as anti-HBs titer had been decreased after 3 years and the desired immune response was seen only in 55.4% of the medical staffs.