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Immunogenicity and safety of PRP-T conjugate vaccine given according to the British accelerated immunisation schedule
R Booy1, S A Taylor, S R Dobson
1John Radcliffe Hospital, University Department of Paediatrics, Oxford.
Insights
A new Haemophilus influenzae type b conjugate vaccine (PRP-T) showed excellent immunogenicity and safety in infants. Routine infant immunization with this vaccine could prevent most Haemophilus influenzae type b disease cases in the UK.
Area of Science:
- Pediatric Vaccinology
- Immunology
- Microbiology
Background:
- Haemophilus influenzae type b (Hib) causes severe invasive disease in young children.
- Effective conjugate vaccines are crucial for preventing Hib infections.
Purpose of the Study:
- To evaluate the immunogenicity and safety of a novel Hib conjugate vaccine, PRP-T.
- To assess the vaccine's efficacy when administered concurrently with routine infant vaccinations.
Main Methods:
- A study involving 107 infants in Oxford.
- PRP-T vaccine administered at 2, 3, and 4 months alongside DTP-polio vaccines.
- Serum antibody levels measured by radioimmunoassay and ELISA before vaccination and at 5 months.
Main Results:
- No serious adverse reactions were observed; minor side effects were not increased.
- Geometric mean antibody titres rose significantly from 0.09 to 5.01 µg/ml post-vaccination.
- 98% of infants achieved protective antibody concentrations (≥0.15 µg/ml).
Conclusions:
- The PRP-T vaccine is safe and highly immunogenic in infants.
- Routine infant immunization with PRP-T at 2, 3, and 4 months is a promising strategy for Hib disease prevention in the UK.
Abstract:
The immunogenicity and safety of a new Haemophilus influenzae type b conjugate vaccine, PRP-T, was studied in 107 infants from the Oxford district. The vaccine was given concurrently with diphtheria, pertussis, tetanus, and polio vaccines at 2, 3, and 4 months of age. Symptoms after immunisation were recorded by a parent. Sera were obtained before the first immunisation and at 5 months of age and the antibodies were measured by both radioimmunoassay and enzyme linked immunosorbent assay (ELISA). No serious adverse reactions were observed and there was no increase in the incidence of expected minor side effects. By radioimmunoassay, the geometric mean titre of serum anticapsular antibody increased from 0.09 micrograms/ml before immunisation to 5.01 micrograms/ml after three immunisations. Ninety eight per cent of children had antibody concentrations consistent with protection (greater than or equal to 0.15 micrograms/ml). IgG antibody concentrations measured by ELISA correlated well with total antibody concentrations measured by radioimmunoassay (r = 0.864). These results provide encouragement that routine immunisation against H influenzae type b at 2, 3, and 4 months of age, could prevent most cases of disease in children in the UK.