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

Background. Pediatric monocomponent formulations of vaccines against hepati tis A and B have been proved to be safe and immunogenic in children. Objectives. To investigate the safety and immunogenicity of a combined hepa titis A/B vaccine in children 1 to 15 years of age. Methods. Three doses of a combined vaccine containing 360 enzyme-linked imm unosorbent assay units of hepatitis A antigen and 10 mu g of hepatitis B su rface antigen were administered in a 0-, 1-, 6-month schedule to three grou ps 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 th e age of the subjects or the vaccine lot and was similar to that described with the monocomponent vaccines. Local and systemic reactions were mostly m ild or moderate and resolved spontaneously. One month after the second dose 100 and 98.8% of all three groups had seroconverted against hepatitis A vi rus 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 a ntibody of 7255 to 11732 mIU/ml in the three groups. Conclusion. The combined pediatric hepatitis A/B vaccine formulation was we ll-tolerated and highly immunogenic in children 1 to 15 years old.