A combined
hepatitis A and B
vaccine,
Twinrix, in a paediatric formulation for ages 1-15 years and in an adult formulation for those ages 16 years and older, became commercially available in Turkey as well as in many countries. It is administered according to a three-dose schedule (0, 1 and 6 months). A reduction in the number of doses would improve the compliance rate and reduce administration costs. Therefore, we planned a trial evaluation of the immunogenicity, safety and reactogenicity profile of a high-dose combined
hepatitis A and B
vaccine, administered in two doses, compared with the profile of a paediatric-dose
combined vaccine, administered in three doses, in healthy children aged 6-15 years. One hundred children were randomly attributed to the two study groups. The first group (paediatric-dose
vaccine group) received the licensed
Twinrix Paediatric, at months 0, 1 and 6; the second group (high-dose
vaccine group) received the high-dose
vaccine, following a 0, 6 months schedule. The reactogenicity was assessed after each
vaccine dose. The immunogenicity was evaluated by testing for anti-HBs and
anti-HAV antibodies. Seroconversion rates and geometric mean titres (GMTs) were compared. Both formulations of the
combined vaccine were well tolerated. The high-dose
combined vaccine administered in two doses, elicits satisfactory immunogenicity profiles, similar to those elicited by the paediatric
vaccine administered in three doses. On completion of the vaccination schedule in the two groups all children were protected against
hepatitis B and immune for
hepatitis A.
Anti-HAV GMTs after completion of the vaccination schedule were 7163 mlU/ml in the paediatric-dose group, 8241 mlU/ml in the high-dose group; anti-HBs GMTs were 8679 and 4583 mlU/ml, respectively. These results indicate that a two-dose schedule, compared with the standard three-dose schedule, offers fewer
injections for satisfactory protection against the two
infections. This means fewer
clinic visits, lower administration costs, better compliance, and higher coverage rate. Therefore, this two-dose schedule can be considered an appropriate regimen for the immunization of children and adolescents against
hepatitis A and B
infection, in the context of school-based immunization programmes.