Abstract
A systematic review was performed to estimate the duration of protection of Hepatitis-B vaccine after primary vaccination during infancy. The number of seropositive participants with anti-HBs antibody titer >= 10 mIU/ml and seronegative participants who had anti-HBs antibody titer <= 10 mIU/ml after booster dose was the main outcome criteria to find out the protection time of Hepatitis-B vaccine. Twelve studies were selected for systematic review. Overall, results from the meta-analysis have revealed that the risk of Anti-HBs Titer <= 10 mIU/ml reduced by 50%. Upon performing the sub-group analysis it was revealed that the overall risk of having Anti-HBs Titre <= 10 mIU/ml was reduced up to 62% among the subjects age 21-30 years (0.38 [0.34, 0.44]; I-2 = 0.0%, p = 0.938). Furthermore, it was observed that the risk of having titre level less than 10 mIU/ml for plasma derived vaccines were to be 56% [0.44, CI 0.33-0.57, I-2 90.9%, p = <0.001]. Vaccination in early infancy does not ensure protection against Hepatitis-B infection. There is a strong correlation between the duration of protection and time elapsed after primary immunization during infancy.