Background: Among the preventing measures for hepatitis B is vaccination against the virus. This study aimed to determine the antibody level against the hepatitis B surface antigen (anti-HBs) and its relation to interferon gamma (IFN-γ) level among the vaccinated staffs and also the reasons for the lack of response in such persons.

Materials and Methods: This cross-sectional study was done on vaccinated staff (n=130) referred to Shahid Chamran Hospital. Using ELISA the samples were studied for anti-HBsAb and INF-γ level. Then, the relationship between antibody level and some indexes (e.g. sex, age, BMI, number of vaccine doses, time past after the last dose and   INF-γ level) was considered.

Results: Among the studied participants, 68.5% and 31.5% had a perfect and failure of immunity response (>10 IU/ml and <10 IU/ml, respectively). There was a direct relationship between the INF-γ and anti-HBs titration (R=0.635). In addition, there was a significant relationship (P<0.05) between anti-HBs titer and some indexes (e.g. BMI, the number of doses and the time interval since the last dose of vaccine); however, no significant relationship was observed between the sex and age on one hand and antibody titration on the other hand.

Conclusion: Failure in INF-γ production against the virus can have a role in immunity response. Hence, measuring the anti-HBs level following the vaccination and also 5 years after are suggested for high risk cases; then, upon which a decision can be made on the reminder dosage.