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Administration of two doses of hepatitis A (HA) vaccine to childrenor = 2 years of age has been shown to be protective. The present study assessed whether HA vaccine can be administered as early as 6 months of age and whether it can be administered concomitantly with a hexavalent (HV) vaccine at this age.In an open label, randomized, parallel group study, the liquid HV vaccine (HEXAVAC) (diphtheria, tetanus, 2-component acellular pertussis, inactivated poliomyelitis vaccine, Haemophilus influenzae type b conjugated to tetanus protein and hepatitis B) was administered at 2, 4, 6, and 12 months of age to all children. HA vaccine (VAQTA) was given at 7 and 13 months in the separate administration group (Group 1) and at 6 and 12 months in the concomitant administration group (Group 2). Serum samples were obtained at 2, 7, 12, and 14 months in Group 1 and at 2, 7, 12, and 13 months in Group 2. The primary immunogenicity outcomes were the seroconversion rates for HA 1 month after the second dose of HA vaccine in initially seronegative subjects, and the seroconversion rates for each HV antigen 1 month after the third dose of the HV vaccine (both at 7 months of age).HA seropositivity rates 1 month after the second dose were 100% in both groups, regardless of initial serostatus. The responses to each HV antigen 1 month after the third dose were similar in both groups. The vaccines were generally well tolerated in both groups regardless of vaccine(s) administered.A schedule of two doses of HA vaccine, 6 months apart beginning at 6 months of age is highly immunogenic and well tolerated when administered alone or concomitantly with HV vaccine at 6 and 12 months of age.

To compare the immunogenicity and safety of a trivalent tetanus-diphtheria (low toxoid content)-inactivated poliomyelitis vaccine, Td-IPV (Revaxis; Pasteur Merièux), with a tetanus-diphtheria (low toxoid content) vaccine, Td (Td-Impfstoff Mérieux; Pasteur Merièux), when administered as a booster to children age 6 to 9 years.A group of 301 children were randomized and vaccinated with Td-IPV (n = 150) or Td (n = 151) in this open, controlled, multicenter trial. Serum specimens were obtained before and 28 days after vaccination. Safety was assessed for up to 28 days postvaccination by parental diary cards. Solicited local and systemic reactions were recorded for 7 days after vaccination.Seroprotection (enzyme-linked immunosorbent assay titer,or =0.10 IU/ml) against tetanus and diphtheria was induced by either Td-IPV or Td in all subjects. Tetanus and diphtheria geometric mean titer were higher after Td (34.0 and 5.74 IU/ml) than after Td-IPV (15.9 and 4.38 IU/ml). All subjects boosted with Td-IPV were seroprotected against each type of poliovirus (neutralizing antibody titer,or =5/dilution). The most frequently reported solicited local and systemic symptoms were pain triggered by movement of the arm (54% vs. 39.1%) and headache (17.3% vs. 7.3%), after Td-IPV and Td, respectively. All other events were similar between the two groups. Reactions were generally mild and all were temporary.A booster dose of Td-IPV induced in all children seroprotection against tetanus, diphtheria and poliomyelitis. The overall safety profile of the two vaccines was acceptable.