High seroprotection rate induced by low doses of a recombinant hepatitis B vaccine in healthy Iranian neonates

Abstract

Low-dose vaccination has been proposed as a cost-saving strategy to implement mass vaccination of neonates with hepatitis B (HB) vaccine, world-wide, particularly in developing countries. The effectiveness of low vaccine doses, however, needs to be evaluated and verified in newborns from different ethnic backgrounds. In this study, a recombinant HB vaccine (Heberbiovac) was administered in three different doses, including the standard 10 μg together with 5 and 2.5 μg to three groups of healthy Iranian neonates. Each group, consisting of 230–260 subjects, received triple doses of vaccine given i.m. at 0, 1.5 and 9 month intervals. Serum samples were collected 2–4 weeks after completion of vaccination, and anti-HBs antibody was quantitated by a sandwich ELISA. Seroprotection (anti-HBs>10 IU/L) was detected in 92, 97.4 and 96.1% of 2.5, 5 and 10 μg vaccine dose recipients, with geometric mean titer (GMT) of 4502, 5824 and 6104 IU/L, respectively. No significant differences were observed in seroprotection rate and GMT between the 10 and 5 μg dose recipients. Both parameters, however, were significantly lower in neonates vaccinated with a 2.5 μg vaccine dose ( P<0.05 and P<0.001, respectively). These findings indicate induction of a strong protective immune response in healthy Iranian neonates by a low dose (5 μg) of the recombinant HB vaccine.