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Haemophilus influenzae type b conjugate vaccine trial in Oxford: implications for the United Kingdom
G Tudor-Williams1, J Frankland, D Isaacs
1University Department of Paediatrics, Radcliffe Infirmary, Oxford.
Insights
This study found that the Haemophilus influenzae type b conjugate vaccine is safe and effective in infants. Immunization at 3, 5, and 9 months generated protective antibody levels with no serious side effects.
Area of Science:
- Pediatrics
- Immunology
- Vaccinology
Background:
- Haemophilus influenzae type b (Hib) infections pose a significant public health risk, particularly in infants.
- Effective conjugate vaccines are crucial for preventing invasive Hib diseases.
Purpose of the Study:
- To evaluate the safety and immunogenicity of a Haemophilus influenzae type b conjugate vaccine in infants.
- To compare the immune response to standard and low doses of the Hib conjugate vaccine.
- To assess the potential impact of Hib conjugate vaccine incorporation into routine infant immunization schedules.
Main Methods:
- A study involving 103 infants immunized at 3, 5, and 9 months with Hib conjugate vaccine alongside routine vaccines.
- A control group of 99 infants received routine vaccines without the Hib conjugate vaccine.
- Comparison of side effects and measurement of serum anticapsular antibody geometric mean titres (GMTs) before and after immunization.
Main Results:
- No serious adverse events were observed in infants receiving the Hib conjugate vaccine.
- The incidence of minor side effects was comparable between vaccine recipients and the control group.
- Both standard and low doses of the Hib conjugate vaccine elicited significant increases in anti-Hib antibody GMTs, indicating protective levels.
- GMTs rose from 0.11 microgram/ml pre-immunization to 26.4 micrograms/ml (standard dose) and 14.6 micrograms/ml (low dose) post-immunization, significantly higher than the 0.06 microgram/ml in unimmunized infants.
- No non-responders to the vaccine were identified.
Conclusions:
- The Haemophilus influenzae type b conjugate vaccine is safe and immunogenic in infants when administered as part of the primary immunization schedule.
- Both tested doses of the vaccine induce protective antibody concentrations.
- Routine incorporation of this vaccine has the potential to prevent a substantial number of Hib disease cases and deaths in the UK.
Abstract:
The safety and immunogenicity of a Haemophilus influenzae type b conjugate vaccine was investigated in 103 infants immunised at 3, 5, and 9 months of age; the infants also received diphtheria, pertussis, and tetanus and polio vaccines. Side effects were compared with 99 matched infants receiving diphtheria, pertussis, and tetanus and polio vaccines only. No serious side effects were observed and the incidence of minor side effects was no greater in the recipients of H influenzae type b conjugate vaccine. Two doses of the vaccine (standard and low) were compared: geometric mean titres of serum anticapsular antibody rose from 0.11 microgram/ml before immunisation to 26.4 micrograms/ml after three immunisations with the standard dose and 14.6 micrograms/ml with the low dose. The geometric mean titre among 21 unimmunized infants at this age was 0.06 micrograms/ml. Both doses therefore generated antibody concentrations likely to be protective after three immunisations. There were no non-responders. Incorporation of an H influenzae type b conjugate vaccine into the primary immunisation schedule has the potential for preventing over 1000 cases of systemic H influenzae type b disease and 50 deaths each year in the United Kingdom.