Introduction: Children in Singapore receive vaccination against hepatitis B virus (HBV) at 0, 1 and 5 or 6 months of age, and vaccination against pertussis, diphtheria, tetanus, and polio at 3, 4 and 5 months of age. Parents often choose to vaccinate with the combined acellular-pertussisinactivated polio-Hib vaccine (DTPa-IPV/Hib). We investigated whether a combined hexavalent vaccine, DTPa-HBV-IPV/Hib, could replace the separate administration of DTPa-IPV/Hib and HBV for the final vaccination at 5 months of age (Trial DTPa-HBV-IPV-075). Materials and Methods: In an open study, 150 children were randomised to complete their vaccination schedule with DTPa-IPV/Hib + HBV or DTPa-HBV-IPV/Hib. Results: One month after the final vaccination, there was no difference between groups in seroprotection rates or antibody concentrations against HBV. Seroprotection rates against diphtheria, tetanus, Hib and polio, as well as vaccine response rates to pertussis antigens were also similar between groups. Local and general symptoms occurred at a similar rate after the third dose of either vaccine. Conclusion: The immunogenicity and reactogenicity of the hexavalent vaccine DTPa-HBV-IPV/Hib (Infanrix hexa, GSK) group is comparable to that of separately administered DTPa-IPV/Hib and HBV vaccines. Combined hexavalent vaccine, DTPa-HBV-IPV/Hib, could replace the separate administration of DTPa-IPV/Hib and HBV for vaccination at 5 months of age, thereby reducing the number of injections required.
Before the introduction of mass vaccination of newborns against hepatitis B virus (HBV) in 1987, almost 10% of children <6 years of age and almost 55% of adults showed evidence of HBV infection in Singapore.1 Like other Asian countries, the primary mode of HBV transmission in Singapore was perinatal.1,2 Interruption of perinatal transmission through vaccination at birth has had a major effect on the epidemiology of HBV in Singapore, with marked reductions in the incidence of acute HBV disease and in chronic carrier rates.1,3,4
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