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[Control of Haemophilus influenzae infections]
1Service des maladies transmissibles et vaccinations, Centre international de l'enfance, Paris, France.
Insights
New conjugate vaccines against Haemophilus influenzae type b (Hib) are safe and effective in infants. Widespread immunization programs are recommended to reduce Hib infections globally.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Public Health
Background:
- Haemophilus influenzae type b (Hib) infections pose a significant health risk, particularly to infants.
- Previous vaccines had limitations in efficacy for certain populations.
Purpose of the Study:
- To review the safety and efficacy of new conjugate Hib vaccines.
- To assess the potential for widespread immunization programs.
Main Methods:
- Review of clinical trials and mass immunization programs.
- Evaluation of immunogenicity, safety, and efficacy data for three conjugate vaccines (HbOC, PRP-OMP, PRP-T).
Main Results:
- Three conjugate Hib vaccines are immunogenic in infants over 6 weeks old.
- Vaccines demonstrate good safety profiles, even with early administration.
- High efficacy observed, including in populations with poor response to non-conjugate vaccines and in individuals with specific health conditions.
- Sustained immunogenicity and duration of immunity covering the period of risk.
Conclusions:
- Conjugate Hib vaccines are safe, effective, and suitable for integration into routine infant immunization programs.
- High immunization coverage is crucial for national-level efficacy.
- Public health initiatives are needed to inform healthcare personnel and families about Hib infections and vaccine benefits.
Abstract:
The results of all clinical trials and mass immunization programmes carried out over the past few years are extremely encouraging and should be the prelude to systematic immunization. Three vaccines that are immunogenic in infants over 6 weeks old, are now available: HbOC linked to diphtheria toxin, PRP-OMP linked to a meningococcus protein, and PRP-T linked to tetanus toxoid. Their safety has been demonstrated particularly when administration at a very early age before the period of risk. Efficacy has been demonstrated, even in population groups who do not respond well to non-conjugate vaccines. Immunogenicity persists even in unfavourable contexts such as individuals with sickle-cell anaemia or leukosis or a previous history of vaccine failure. The duration of immunity amply covers the period of risk and probably a longer because of the booster effect of natural infections. The possibility of combining Hib vaccine with other routine immunizations in infancy will reduce the cost of this additional immunization. Thus it is possible to envisage its integration into immunization programmes in developing countries. Cost/benefit studies show advantages. What is needed now is to achieve high immunization coverage, guaranteeing efficacy of immunization at national level, by ensuring that health personnel as well as families are fully informed about the seriousness of Hib infections and the good tolerance and efficacy of the conjugate vaccines.