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