Evaluation of Haemophilus influenzae type b conjugate vaccine (meningococcal protein conjugate) in Canadian infants.

Objective: To assess adverse effects and immune responses with a three-dose series of Haemophilus influenzae type b meningococcal protein conjugate (PedvaxHIB or Hib.OMP) vaccine, including any immunological response alterations from concurrent administration with routine vaccines for infants.

Design: Randomized, controlled trial with treatment group crossover for dose 3.

Setting: Two public health units near Vancouver.

Participants: One hundred and ten healthy infants eight to 14 weeks old were enrolled; 105 completed the study (95%).

Interventions: All participants received two doses of diphtheria-pertussis-tetanus (dpt) vaccine (at two and four months of age) and one dose of measles-mumps-rubella (mmr) vaccine at 12 months. In each instance, Hib.OMP was given either concurrently in another limb or after a delay of two weeks (after dpt) or four weeks (after mmr).

Main Outcome Measures: Adverse effects, particularly fever and local erythema, were monitored by parents for 72 h after each dose of Hib.OMP vaccine. Five blood samples were taken at prescribed intervals to assess responses to each dose of Hib.OMP and to selected other vaccine antigens.

Main Results: Follow-up was obtained after all 322 doses of Hib.OMP. Local adverse effects were infrequent and mild: 13% had redness, 17% tenderness. Systemic effects in those given Hib.OMP alone included fever in 8%, irritability in 29%. Anti-polyribose-ribitol phosphate (prp) responses to Hib.OMP were not impaired by coadministration with dpt or mmr vaccines, nor were tetanus or diphtheria antitoxin levels or rubella or measles response rates affected. After two doses of Hib.OMP, 92% were seropositive and 64% had greater than 1.0 μg/mL of anti-prp. After three doses, 100% were seropositive and 82% exceeded 1.0 μg/mL.

Conclusion: Hib.OMP vaccine was well tolerated, immunogenic and compatible with vaccines routinely given to infants in Canada.