A study to assess the immunogenicity, reactogenicity and safety of hepatitis A vaccine administered subcutaneously to patients with congenital coagulation disorders

The objective was to compare the immunogenicity, reactogenicity and safety of an inactivated hepatitis A vaccine administered subcutaneously to patients with congenital coagulation disorders. Subjects, 97 patients with congenital coagulation disorders (67 men aged > 16 and 30 children aged less than or equal to 16 years), received hepatitis A vaccine administered at 1440 ELISA (enzyme linked immunosorbent assay) units (ELU) to the adult group and at 720 ELU to the child group at 0 and 6 months by the subcutaneous route. The vaccine was well tolerated, with the incidence of adverse events decreasing with subsequent administration of vaccine. Overall, 90% of subjects seroconverted 1 month after the booster (95% confidence interval 76-97%), with 100% seroconversion occurring in the child group compared with 85% in the adult group. There was a corresponding progressive rise in geometric mean titres in each group and no significant difference in the geometric mean titres was found between the two groups. Of the subjects, 29% were HIV positive, 3% of children compared with 40% of adults. A lower rate of seroconversion was observed in subjects with low CD4 counts. Administration of two doses of an inactivated hepatitis A vaccine at 1440 ELU in adults and 720 ELU in children is safe and highly immunogenic when given by the subcutaneous route.