ABSTRACT
Hepatitis B is one of the most prevalent chronic and persistent hepatitis infections which may lead to chronic hepatitis and hepato-cellular carcinoma. Since hospital personnel are more susceptible to hepatitis B this study was done to determine the relation between number of hepatitis B vaccinations and the presence of anti HBS antibody in personnel working in a large hospital in Tehran. This was a cross-Sectional study conducted in 2010 on 530 personnel working in Khatam-ol-Anbiya Hospital. Blood samples were collected from the subjects selected through convenience sampling and the level of anti-HBS antibody checked: antibody levels >10 mIU/ml were considered to be protective. Antibody levels were less than the stated cut-off in 78 individuals, [14.7%]. Mean antibody levels were 9.5 mIU/ml in the 27 unvaccinated persons; 86.6 mIU/ml in 7 individuals who had received the vaccine only once; 160 mIU/ml in the 32 who had been vaccinated twice; 192 mIU/ml after 3 doses of the vaccine in 276 persons and in the 58 subjects who had received >3doses, the mean level of the antibody was 321 mIU/ml, [p=0.001]. Anti-HBS antibody levels show a significant rise after repeated vaccinations