Anticapsular Serum Antibody Concentration and Protection against Pneumococcal Colonization among Children Vaccinated with 7-Valent Pneumococcal Conjugate Vaccine

• Published in: Clinical infectious diseases Vol. 44; no. 9; pp. 1173 - 1179
• Main Authors: Millar, Eugene V., O'Brien, Katherine L., Bronsdon, Melinda A., Madore, Dace, Hackell, Jill G., Reid, Raymond, Santosham, Mathuram
• Format: Journal Article
• Language: English
• Published: Chicago, IL The University of Chicago Press 01.05.2007; University of Chicago Press; Oxford University Press
• Subjects: Antibiotics; Antibodies; Antibodies, Bacterial - blood; Articles and Commentaries; Babies; Bacterial Capsules - immunology; Bacterial diseases; Biological and medical sciences; Children; Clinical outcomes; Clinical trials; Conjugate vaccines; Correlation analysis; Disease prevention; Dosage; Experimentation; Female; Human bacterial diseases; Humans; Immune response; Immunization; Immunoglobulins; Indians, North American; Infant; Infectious diseases; Male; Medical sciences; Nasopharynx - microbiology; Osmolar Concentration; Pediatrics; Pneumococcal Infections - immunology; Pneumococcal Infections - microbiology; Pneumococcal Infections - prevention & control; Pneumococcal vaccine; Pneumococcal Vaccines - therapeutic use; Regression analysis; Respiratory diseases; Serotyping; Southwestern United States; Staphylococcal infections, streptococcal infections, pneumococcal infections; Streptococcus pneumoniae; Streptococcus pneumoniae - classification; Streptococcus pneumoniae - immunology; Streptococcus pneumoniae - isolation & purification; Vaccination; Vaccines; Vaccines, Conjugate - therapeutic use; Southwestern United States; Southwestern states; Human; Antibody; Concentration; Polyvalent vaccine; Streptococcus pneumoniae; Infection; Streptococcaceae; Streptococcal infection; Bacteriosis; Bacteria; Micrococcales; Serum; Child; Pneumococcal infection; Protection; Colonization
• ISSN: 1058-4838; 1537-6591
• DOI: 10.1086/513199

Background. Pneumococcal conjugate vaccines prevent invasive and noninvasive disease due to infection with vaccine serotypes. Pneumococcal conjugate vaccines also prevent nasopharyngeal acquisition of vaccine serotypes, although the mechanism is incompletely understood. Methods. An efficacy trial of a 7-valent pneumococcal conjugate vaccine was conducted on the Navajo and White Mountain Apache reservations, located in the Southwestern United States; group C meningococcal conjugate vaccine was the control vaccine. Infants were randomized to receive 7-valent pneumococcal conjugate vaccine or group C meningococcal conjugate vaccine at 2, 4, 6, and 12 months of age. Immunogenicity and nasopharyngeal colonization studies were nested in the efficacy trial. We analyzed the correlation between serotype-specific serum IgG concentration at 7 and 13 months of age and nasopharyngeal acquisition of disease at 12 and 18 months of age, respectively. We adjusted for potential confounders using multivariate logistic regression. Results. Among 203 subjects, we observed 60 acquisitions of vaccine-type pneumococci, including 19 acquisitions of serotype 19F (31.7%), and 17 acquisitions of serotype 23F (28.3%). Among recipients of 7-valent pneumococcal conjugate vaccine, increased serotype-specific serum IgG was associated with a reduction in nasopharyngeal acquisition of serotype 23F (relative risk, 0.53; 95% confidence interval, 0.31–0.93) but was not associated with a reduction in acquisition of serotype 19F (relative risk, 1.07; 95% confidence interval, 0.57–2.03). Among group C meningococcal conjugate vaccine recipients, serotype-specific serum IgG was not associated with a reduction in nasopharyngeal acquisition for either serotype. Conclusion. An increase in serum antibody concentration was associated with reduced acquisition of serotype 23F pneumococcus (but not with reduced acquisition of serotype 19F pneumococcus) among recipients of 7-valent pneumococcal conjugate vaccine. Differences in antibody concentration, in the functional characteristics of antibody, or in antibody kinetics during infancy may account for differences in carriage protection.