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Antibody responses to four Haemophilus influenzae type b conjugate vaccines
H Käyhty1, J Eskola, H Peltola
1Department of Bacteriology, National Public Health Institute, Helsinki, Finland.
Insights
This study compared Haemophilus influenzae type b conjugate vaccines in infants, adults, and children. PRP-T showed a better infant response after two doses, while all vaccines were equally effective in adults and children.
Area of Science:
- Immunology
- Vaccinology
- Pediatrics
Background:
- Haemophilus influenzae type b (Hib) poses a significant health risk, particularly to young children.
- Conjugate vaccines are crucial for preventing Hib infections, but their immunogenicity can vary.
- Understanding antibody responses to different Hib conjugate vaccines is vital for public health strategies.
Purpose of the Study:
- To compare the serum antibody responses to four Haemophilus influenzae type b capsular polysaccharide-protein conjugate vaccines (PRP-D, HbOC, C7p, and PRP-T).
- To evaluate vaccine efficacy across different age groups: infants, adults, and 2-year-old children.
Main Methods:
- Serum antibody concentrations were measured using a Farr-type radioimmunoassay.
- Infants received two vaccine doses at 4 and 6 months; adults and children received one dose.
- Four conjugate vaccines were tested: PRP-D, HbOC, C7p, and PRP-T.
Main Results:
- Infants showed a higher response to PRP-T after two doses compared to PRP-D, HbOC, and C7p.
- PRP-D demonstrated a significantly lower geometric mean antibody concentration in infants post-vaccination.
- Adults and 2-year-old children exhibited high and comparable antibody responses to all tested Hib conjugate vaccines after a single dose.
Conclusions:
- PRP-T appears to be more immunogenic in infants after a two-dose regimen.
- All tested Haemophilus influenzae type b conjugate vaccines are highly immunogenic in adults and young children with a single dose.
- Vaccine selection may need to consider age-specific immunogenicity for optimal Hib prevention.
Abstract:
Serum antibody responses to four Haemophilus influenzae type b capsular polysaccharide-protein conjugate vaccines (PRP-D, HbOC, C7p, and PRP-T) were studied and compared in 175 infants, 85 adults and 140 2-year-old children. Antibodies to the H influenzae type b polysaccharide vaccines were determined with a Farr-type radioimmunoassay. The infants received two doses of vaccine at the ages of 4 and 6 months. After the first dose of vaccine, the geometric mean antibody concentration measured at the age of 6 months was 0.09 to 0.10 mg/L, only marginally higher than that measured before immunization in all infants who had received PRP-D, HbOC, or C7p but increased to 0.82 mg/L in those who had received PRP-T. One month after the second dose, the geometric mean antibody concentration was increased in all vaccine groups. No significant differences were noted between recipients of HbOC, C7p, or PRP-T (geometric mean antibody concentrations, 4.32, 3.10, and 6.10 mg/L, respectively), whereas the PRP-D recipients had a significantly lower geometric mean antibody concentration (0.63 mg/L). In contrast, PRP-D, HbOC, C7p, and PRP-T were all highly immunogenic in adults, with no differences noted among them. The 2-year-old children also responded to one dose of these vaccines with a high antibody concentration.