Long-term efficacy of hepatitis B vaccination in healthcare workers of Oil Company Hospital, Tehran, Iran (1989-2005)

Objective This study was conducted to evaluate the 16-year efficacy of hepatitis B virus (HBV) vaccine in healthcare workers of Oil Company Hospital, Tehran, Iran. Methods Two hundred healthcare workers were enrolled in the study in 1989. All HBV markers were tested and those with positive HBV markers, positive antihepatitis C virus or anti-HIV were excluded from the study. The remaining participants received three doses of HBV vaccine and again all of our participants were reevaluated in 2005. Hepatitis B surface antigen (HBsAg), antihepatitis B surface antibody (anti-HBsAb), and antihepatitis B core antibody (anti-HBcAb) were checked in all participants and those with anti-HBcAb above 10 IU/I were excluded from the final evaluation. Results No participant was positive for HBsAg in either 1989 or 2005. Protective levels of anti-HBsAb were absent in all participants in 1989, but present in 67 (80.7%) participants in 2005 (P<0.001). Anti-HBsAb titer after vaccination was significantly higher in female participants than in male participants (P=0.01). Mean anti-HBsAb titer was 640 +/- 411.71 IU/I (range: 2-1000 IU/I) and the lowest protective titer was 12 IU/I. Conclusion According to our results, 80.7% of our participants had a protective titer of anti-HBsAb 16 years after vaccination. Although all anti-HBc positive participants were free of clinical hepatitis and were negative for HBsAg, hepatitis B vaccination was proved to be highly effective in preventing clinically significant infection and chronic carrier status up to 16 years after the primary vaccination. Hence, HBV revaccination may not be mandatory in healthcare workers, according to their sufficient long-term level of anti-HBsAb.