Estimation of Anti Hbs antibody titer in adults during 5-10 years period following three doses of vaccine

Abstract

Health care professional are a high risk group for Hepatitis B and are advised vaccination against hepatitis B. The protective antibodies induced by Hepatitis B vaccination wane gradually over period of time and may reach very low or even undetectable levels. A cross sectional prospective study was undertaken to investigate the persistence of anti-HBs levels in health care professionals who had been immunized with HBV vaccine and the need for booster doses of the vaccine. In this cross-sectional study, health care professionals (18 -55 yrs of age) who had received full course of HBV vaccination were sampled and tested for anti-HBs from May 2010 to June 2011. Plasma samples were tested for anti-HBs using ELISA. Titer >=10 mIU/mL was considered to be seroprotective. Individuals with titre <10 mIU/mL were advised full three doses of vaccine. A total of 112 samples were collected. Protective antibody levels were detected in 99.9% of subjects one year after vaccination. It decreased to 80.96% by 5 years after vaccination, and further decreased to 46.16% in 10 years after vaccination. Sero protection rates decreased significantly with increasing time from last vaccination due to waning anti-HBs titer (P<0.001).According to the above mentioned results, for a high risk group population such as medical students and residents, who are at continuous exposure to HBV, it is reasonable to determine the anti HBsAb response at one month post vaccination However, in order to confirm the persistence of immune protection, we strongly suggest detection of the anti-HBsAb titer at 5 - 10 years after the last inoculation.