Related Experiment Videos
Enhanced antibody responses in infants given different sequences of heterogeneous Haemophilus influenzae type b
D P Greenberg1, J M Lieberman, S M Marcy
1Division of Pediatric Infectious Diseases, Harbor-UCLA Medical Center, Torrance 90502.
Insights
Different Haemophilus influenzae type b (Hib) conjugate vaccine schedules were evaluated for safety and immunogenicity in infants. Schedules starting with PRP-OMP and followed by HbOC or PRP-T vaccines showed the highest antibody levels, suggesting optimal protection.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Haemophilus influenzae type b (Hib) remains a significant cause of invasive disease in infants and young children.
- Heterogeneous conjugate vaccine schedules are being explored to optimize immunogenicity and safety.
- Understanding the comparative immunogenicity of different Hib vaccine formulations and sequences is crucial for public health.
Purpose of the Study:
- To assess the safety and immunogenicity of various vaccination schedules using different Haemophilus influenzae type b (Hib) conjugate vaccines.
- To compare the antibody responses elicited by single and heterogeneous Hib vaccine sequences in infants.
- To identify optimal Hib vaccination schedules for infants, particularly those at high risk for invasive Hib disease.
Main Methods:
- A randomized trial involving 300 infants assigned to six different vaccination schedules.
- Administration of single or heterogeneous Hib conjugate vaccines (PRP-OMP, PRP-T, HbOC) at 2, 4, and 6 months of age.
- Monitoring for serious and minor adverse reactions and measuring antibody responses to evaluate immunogenicity.
Main Results:
- No serious adverse reactions were linked to heterogeneous Hib vaccine use; minor reactions were comparable across groups.
- PRP-OMP vaccine induced an initial antibody response after the first dose, but booster responses were not significant.
- PRP-T vaccine showed a good response after two doses, while HbOC required three doses for a similar antibody level.
- Schedules initiating with PRP-OMP at 2 months, followed by HbOC or PRP-T at 4 and 6 months, yielded the highest antibody levels.
Conclusions:
- All evaluated Hib vaccine schedules were immunogenic in infants.
- Vaccination schedules starting with PRP-OMP at 2 months, followed by HbOC or PRP-T, appear most effective in inducing high antibody levels.
- These optimized schedules may offer the best protection against invasive Hib disease, especially in high-risk populations like American Indian children.
Abstract:
To evaluate the safety and immunogenicity of differing sequences of heterogeneous Haemophilus influenzae type b (Hib) conjugate vaccines, we randomly assigned 300 infants to one of six vaccination schedules. At 2, 4, and 6 months of age, subjects were given single or heterogeneous vaccines: Hib polysaccharide (PRP) conjugated to mutant diphtheria toxin (HbOC), PRP conjugated to outer-membrane protein of Neisseria meningitidis (PRP-OMP), or PRP conjugated to tetanus toxoid (PRP-T). No serious reactions were attributable to immunization with heterogeneous vaccines, and there were few significant differences in the rates of minor adverse reactions among groups. PRP-OMP was the only vaccine that induced an antibody response after the first dose, but significant booster responses were not seen after the second and third doses. Subjects given PRP-T vaccine responded well after two doses, but three doses of HbOC vaccine were needed for an equivalent antibody response. All the Hib vaccine schedules evaluated were immunogenic, and schedules initiated by PRP-OMP vaccine at 2 months of age, followed by two doses of either HbOC or PRP-T vaccine at 4 and 6 months of age, induced the highest antibody levels after each dose. Such schedules may be the best for protecting infants and children who are at greatest risk of having invasive Hib disease, such as American Indian children.