Immunogenicity and reactogenicity of Haemophilus influenzae type b-meningococcus group B outer membrane protein conjugate vaccine in children 2-60 months of age

Area of Science:

• Immunology
• Vaccinology
• Pediatrics

Background:

• Haemophilus influenzae type b (Hib) and Neisseria meningitidis group B are significant causes of bacterial meningitis.
• Conjugate vaccines combining Hib and meningococcal components offer a strategy for broad protection.

Purpose of the Study:

• To evaluate the immunogenicity and safety of a novel Haemophilus influenzae b - Neisseria meningitidis group B outer membrane protein conjugate vaccine (Hib-OMP).
• To determine the optimal age for vaccination and the persistence of antibody response.

Main Methods:

• A total of 571 children aged 2-60 months received either two doses (infants 2-11 months) or one dose (children 12-60 months) of the Hib-OMP vaccine.
• Sera were collected pre-immunization, post-immunization, and at 1-month and 1-year follow-ups.
• Geometric mean antibody concentrations (GMC) and the proportion of vaccinees with detectable antibodies (≥0.125 µg/ml) were measured.

Main Results:

• The Hib-OMP vaccine was immunogenic across all age groups, with GMCs increasing with age post-immunization.
• Detectable antibodies failed to develop in only 0.5% after primary immunization.
• Antibody levels waned in 4.8% of children by 1 year post-immunization, with a higher rate in infants vaccinated before 12 months of age.

Conclusions:

• The Hib-OMP conjugate vaccine is immunogenic in children from 2 months of age, demonstrating efficacy as early as 3-5 months.
• The findings support the potential of this vaccine for early childhood immunization.
• Further assessment is needed to determine the necessity and optimal timing for booster immunizations.