title: Prevention of Haemophilus influenzae type b colonization by vaccination: correlation with serum anti-capsular IgG concentration.
abstract: Concentrations of serum anti-Haemophilus influenzae type b (anti-Hib) capsular polysaccharide (CPS) >/=0.15 and >/=1.0 microgram/mL are widely used as surrogates for protection against invasive Hib disease. However, the relationship between serum anti-Hib CPS following immunization and protection against colonization is not known, making it difficult to evaluate new Hib vaccines or combination vaccines. In the Dominican Republic, nasopharyngeal swabs were collected from 546 9-month-old infants who had received Hib conjugate vaccine at ages 2, 4, and 6 months and from 600 unvaccinated infants of the same age. The prevalence of Hib colonization was lower among vaccinated infants than among unvaccinated infants (0.9% vs. 2.3%). Among vaccinated infants, protection against colonization was significantly correlated with anti-Hib CPS concentrations >/=5 microgram/mL 1 month following the third dose of vaccine. These results suggest that the concentration of serum anti-Hib CPS needed for protection against colonization is greater than that needed for protection for invasive disease.
authors.affiliation: Clinica Infantil Robert Reid Cabral, Santo Domingo, Dominican Republic.
authors.forename: J
authors.initials: J
authors.lastname: Fernandez
authors.forename: O S
authors.initials: OS
authors.lastname: Levine
authors.forename: J
authors.initials: J
authors.lastname: Sanchez
authors.forename: S
authors.initials: S
authors.lastname: Balter
authors.forename: L
authors.initials: L
authors.lastname: LaClaire
authors.forename: J
authors.initials: J
authors.lastname: Feris
authors.forename: S
authors.initials: S
authors.lastname: Romero-Steiner
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood*; D016667:Bacterial Capsules / Q000276:immunology*; D006192:Haemophilus Infections / Q000517:prevention & control*; D018073:Haemophilus Vaccines / Q000276:immunology*; D006193:Haemophilus influenzae / Q000276:immunology*; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood*; D007223:Infant; D011135:Polysaccharides, Bacterial / Q000276:immunology*; D014611:Vaccination
chemical_list: D000907:Antibodies, Bacterial; D018073:Haemophilus Vaccines; C044237:Haemophilus influenzae type b polysaccharide vaccine; D007074:Immunoglobulin G; D011135:Polysaccharides, Bacterial