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Published on: December 1, 2017
Comparative trial in infants of four conjugate Haemophilus influenzae type b vaccines
M D Decker1, K M Edwards, R Bradley
1Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, Tennessee 37232.
Insights
Four conjugate Haemophilus influenzae type b vaccines were tested in infants. All were safe, but PRP-T and PRP-CRM showed superior antibody response compared to PRP-OMP and PRP-D for infant immunization.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Haemophilus influenzae type b (Hib) conjugate vaccines are crucial for infant immunization.
- Evaluating the immunogenicity and safety of different Hib conjugate vaccine formulations is essential.
Purpose of the Study:
- To compare the immunogenicity and reactogenicity of four different conjugate Haemophilus influenzae type b vaccines in infants.
- To determine the suitability of these vaccines for primary infant immunization series.
Main Methods:
- A double-blind, randomized trial involving infants receiving vaccines at 2, 4, and 6 months of age.
- Assessing antibody levels and adverse reactions following vaccination with four distinct Hib conjugate vaccines: PRP-CRM, PRP-T, PRP-OMP, and PRP-D.
- Comparing serologic responses, including mean antibody levels and the percentage of infants achieving protective antibody titers (≥1 microgram/ml).
Main Results:
- All four vaccines demonstrated good safety profiles with few and minor adverse reactions, comparable to conventional diphtheria-tetanus-pertussis vaccine.
- Significant differences in immunogenicity were observed: PRP-T and PRP-CRM elicited substantially higher mean antibody levels than PRP-OMP and PRP-D after three doses.
- PRP-OMP showed a clinically relevant antibody elevation after two doses, with a further modest increase after the third dose. PRP-D resulted in the lowest antibody levels, with only 29% of infants reaching protective titers.
Conclusions:
- All tested Haemophilus influenzae type b conjugate vaccines are safe for infant immunization.
- PRP-T and PRP-CRM are highly immunogenic and suitable for primary infant immunization series.
- PRP-OMP also shows promise, particularly with its response after two doses, while PRP-D appears less effective for primary infant immunization based on antibody response.
Abstract:
We performed a double-blind, randomized trial to compare the immunogenicity and reactogenicity of four conjugate Haemophilus influenzae type b vaccines given to infants 2, 4, and 6 months of age. Adverse reactions attributable to the vaccines were few and minor. The rates of systemic reactions did not differ among the various vaccines and were similar to those seen among children receiving conventional diphtheria-tetanus-pertussis vaccine. However, the four conjugate H. influenzae type b vaccines differed markedly in ability to stimulate antibody production. Mean antibody levels after three injections of polyribosylribitol phosphate conjugated with mutant diphtheria protein (PRP-CRM) or polyribosylribitol phosphate conjugated with tetanus toxoid (PRP-T) were 3.08 micrograms/ml and 3.64 micrograms/ml, respectively, significantly higher than those after the use of polyribosylribitol phosphate conjugated with outer-membrane protein of Neisseria meningitidis (PRP-OMP) (1.14 micrograms/ml) or polyribosylribitol phosphate conjugated with diphtheria toxoid (PRP-D) (0.28 microgram/ml). Only PRP-OMP produced a clinically pertinent elevation in antibody level after two injections (0.84 microgram/ml); the third injection of PRP-OMP produced a modest but statistically significant further elevation in mean antibody level (1.14 micrograms/ml). Only 29% of infants receiving PRP-D had antibody levels of 1 micrograms/ml, compared with 55%, 75%, and 83% of those receiving PRP-OMP, PRP-CRM, and PRP-T, respectively. We conclude that all four vaccines are safe and that all but PRP-D appear appropriate for use in a primary immunization series during infancy. The unique serologic response to PRP-OMP offers both advantages and disadvantages in comparison with PRP-CRM and PRP-T.
