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Decreased Haemophilus colonization in children vaccinated with Haemophilus influenzae type b conjugate vaccine
T V Murphy1, P Pastor, F Medley
1Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas 75235-9063.
Insights
Haemophilus influenzae type b conjugate vaccination significantly reduced pharyngeal colonization in healthy children. This conjugate vaccine may decrease transmission of this bacterium among children in day care settings.
Area of Science:
- Pediatric Infectious Diseases
- Vaccinology
- Microbiology
Background:
- Invasive Haemophilus disease incidence has declined in unvaccinated children post-conjugate vaccine introduction.
- Haemophilus influenzae type b (Hib) is a significant cause of invasive bacterial disease in young children.
Purpose of the Study:
- To investigate the impact of conjugate vaccination on Haemophilus influenzae type b pharyngeal colonization.
- To determine if Hib conjugate vaccination reduces bacterial carriage in healthy children.
Main Methods:
- Prospective, bimonthly survey of pharyngeal colonization with H. influenzae type b in children attending day care.
- 1188 pharyngeal cultures from 283 healthy children (18-59 months) with documented vaccination status (unconjugated polysaccharide vaccine [PRP] or conjugate vaccine).
- Multivariate analysis to assess the association between vaccination status and colonization rates.
Main Results:
- Conjugate vaccination demonstrated significant efficacy in preventing H. influenzae type b colonization: 64% in unmatched analysis and 81% in matched analysis.
- A statistically significant reduction in colonization was observed among children who received the conjugate vaccine (p = 0.02).
- Unconjugated polysaccharide vaccine (PRP) showed no significant effect on H. influenzae type b colonization.
Conclusions:
- Conjugate vaccination effectively decreases H. influenzae type b pharyngeal colonization in healthy children.
- Reduced colonization may lead to decreased transmission of H. influenzae type b among children in community settings.
- Findings support the role of conjugate vaccines in controlling the spread of Hib infections.
Objective:
The incidence of invasive Haemophilus disease has unexpectedly decreased in unvaccinated children since the introduction of conjugate vaccine in the United States. The purpose of this study was to determine whether conjugate vaccination decreases colonization with Haemophilus influenzae type b.
Design:
This study was a prospective, bimonthly survey of pharyngeal colonization with H. influenzae type b in children attending day care from October 1987 through September 1989. Vaccination status was determined from the medical record.
Subjects:
We obtained 1188 pharyngeal cultures from 283 healthy children, 18 to 59 months of age; 51 children had received unconjugated polysaccharide vaccine (PRP), and 89 had received conjugate vaccine (94% PRP-diphtheria toxoid).
Measurements And Results:
Multivariate analysis was used to test the possibility of an association between vaccination status and the rate of colonization with H. influenzae type b. Among children known to be exposed to at least one child with a positive culture result, the efficacy of conjugate vaccination to prevent H. influenzae type b colonization in an unmatched analysis was 64% (95% confidence interval: 5%, 86%; p = 0.02) and in a matched analysis 81% (95% confidence interval: 7%, 96%; p = 0.02). No effect on colonization was found with PRP vaccination.
Conclusions:
Conjugate vaccination decreases H. influenzae type b pharyngeal colonization and thereby may decrease transmission of this agent among healthy children.