The current recommended infant vaccination schedules require many
injections at multiple sites, which increase stress for infants and parents and may create challenges to vaccination compliance. Therefore,
combination vaccines, which reduce the number of
injections at each medical visit, can be an essential method to improve compliance. The objective of this study was to assess the safety and immunogenicity of an investigational, liquid, hexavalent, pediatric
vaccine at 2, 4, 6, and 12-14 months of age. In this multicenter, open-label controlled study, 756 infants were randomized in approximately equal numbers to receive 0.5mL intramuscular dose of diptheria-
tetanus-
pertussis-
polio-Haemophilus influenzae type b+hepatitis B
vaccine, or 1 of 3 double-blind investigational formulations. All formulations included a
hepatitis B surface antigen (
HBsAg) concentration of 10μg/0.5mL. The three
hexavalent vaccine formulations used in this study contained either Hib polyribosylribitol
phosphate (PRP) conjugate component (
tetanus toxoid [
PRP-T, 12μg] or Neisseria meningitidis outer
membrane protein complex [PRP-OPMC, 3μg or 6μg]): a minimum acceptable postdose 3 antibody response rate for each
antigen was defined by the lower limit of a 95% confidence interval exceeding a prespecified target. Rates of adverse events (AEs) were similar among groups, with a trend for increased solicited
vaccine-related
injection-site reactions (
pain,
erythema, swelling) with increasing
PRP-OMPC dose. No serious
vaccine-related AEs were reported in the investigational groups. Both
PRP-OMPC formulations met prespecified acceptability criteria for all
antigens: PRP,
HBsAg,
pertussis,
diphtheria,
tetanus and poliovirus. The
PRP-T formulation met the acceptability criterion for antibody responses to all
antigens other than PRP at postdose 3. Postdose 4 responses were adequate for all
antigens in all formulations. All
vaccine formulations were well-tolerated. Both
PRP-OMPC formulations met prespecified immunogenicity criteria of
PRP-OMPC evaluation.