A combined vaccine against hepatitis A and B in children and adolescents

Background. Pediatric monocomponent formulations of vaccines against hepatitis A and B have been proved to be safe and immunogenic in children. Objectives. To investigate the safety and immunogenicity of a combined hepatitis A/B vaccine in children 1 to 15 years of age. Methods. Three doses of a combined vaccine containing 360 enzyme-linked immunosorbent assay units of hepatitis A antigen and 10 mu g of hepatitis B surface antigen were administered in a 0-, 1-, 6-month schedule to three groups of children: a group of 1- to 6-year-olds (n = 60); and two groups of 6- to 15-year-olds (both n = 60), Results. Reactogenicity, assessed using diary cards, was not affected by the age of the subjects or the vaccine lot and was similar to that described with the monocomponent vaccines. Local and systemic reactions were mostly mild or moderate and resolved spontaneously. One month after the second dose 100 and 98.8% of all three groups had seroconverted against hepatitis A virus and hepatitis B virus, respectively. After the third dose all subjects were seropositive for both components, with geometric mean titers for anti hepatitis A virus of 6518 to 8907 mIU/ml and for anti-hepatitis B surface antibody of 7255 to 11732 mIU/ml in the three groups. Conclusion. The combined pediatric hepatitis A/B vaccine formulation was well-tolerated and highly immunogenic in children 1 to 15 years old.