Long-term immunogenicity and efficacy of a recombinant hepatitis B vaccine in Egyptian children.

In 1992, Egypt adopted a hepatitis B vaccine schedule at 2, 4 and 6 months of age. We evaluated the long-term immunogenicity and efficacy of vaccination using this schedule in 180 children whose time lapse since last vaccination varied between 1 month and 5 years. None of the participants had clinical hepatitis, HBsAg was not detected in any participant and all but one had negative results for anti-HBc test. Although a high seroprotection rate (93.3%) was elicited 1 month after vaccination, there were low initial anti-HBs concentrations and both declined rapidly over time. Thus, the short interval (2 months) between the second and third doses of vaccine is less desirable in the long term. We recommend booster inoculations for all previously vaccinated children and a new vaccination schedule at 1, 2 and 9 months.