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Haemophilus influenzae type b reemergence after combination immunization
Nik G Johnson1, Jens U Ruggeberg, Gail F Balfour
1St George's University of London, London, United Kingdom.
Emerging Infectious Diseases
|May 19, 2006
Summary
The diphtheria/tetanus/acellular pertussis-Haemophilus influenzae type b (DTaP-Hib) vaccine may be linked to increased Hib disease in children. Lower antibody levels and avidity were observed after vaccination, especially with more doses.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Immunology
Background:
- An increase in Haemophilus influenzae type b (Hib) infections has been observed in British children.
- This rise has been anecdotally linked to the widespread use of combination vaccines including Hib.
- The diphtheria/tetanus/acellular pertussis-Hib (DTaP-Hib) vaccine is one such combination vaccine.
Purpose of the Study:
- To investigate the association between DTaP-Hib vaccination and Hib immunity in young children.
- To measure anti-Hib antibody concentration and avidity post-booster vaccination.
- To assess the prevalence of Hib pharyngeal carriage in relation to vaccination history.
Main Methods:
- Measurement of anti-polyribosyl-ribitol phosphate (PRP) antibody concentration and avidity.
- Analysis of samples from 176 children aged 2-4 years before and after a Hib booster.
- Assessment of Hib pharyngeal carriage in study participants.
Main Results:
- Low antibody concentrations and avidity indices were observed post-vaccination.
- Lower antibody levels and avidity were inversely related to the number of prior DTaP-Hib doses received.
- Hib was detected in 2.1% of the children studied.
Conclusions:
- The findings suggest an association between DTaP-Hib vaccine combinations and clinical Hib disease.
- This association may be mediated by effects on antibody concentration and avidity.
- Further research is warranted to understand the long-term impact of DTaP-Hib on Hib immunity.