title: Inferior quantitative and qualitative immune responses to pneumococcal conjugate vaccine in infants with nasopharyngeal colonization by Streptococcus pneumoniae during the primary series of immunization.
abstract: BACKGROUND
  Heightened immunogenicity, measured one month after the primary series of pneumococcal conjugate vaccine (PCV), in African children was previously hypothesized to be due to increased rates of nasopharyngeal pneumococcal colonization during early infancy.
  
  
  METHODS
  We analyzed the effect of selected vaccine-serotype (6B, 19F and 23F) nasopharyngeal colonization prior to the first PCV dose or when colonized for the first time prior to the second or third (2nd/3rd) PCV dose on serotype quantitative and qualitative antibody responses.
  
  
  RESULTS
  Colonization prior to receiving the first PCV was associated with lower geometric mean antibody concentrations (GMCs) one month after the third dose of PCV and six months later to the colonizing-serotype. Colonized infants also had lower geometric mean titers (GMTs) on opsonophagocytosis activity assay (OPA) and a lower proportion had titers ≥ 8 against the colonizing serotypes (19F and 23F) post vaccination. Colonization occurring only prior to the 2nd/3rdPCV dose was also associated with lower GMCs and OPA GMTs to the colonizing-serotype. The effect of colonization with serotypes 19F and 23F prior to PCV vaccination had a greater effect on a lower proportion of colonized infants having OPA titers ≥ 8 than the effect of colonization on the lower proportion with antibody ≥ 0.35 μg/ml.
  
  
  CONCLUSIONS
  Infant nasopharyngeal colonization at any stage before completing the primary series of PCV vaccination was associated with inferior quantitative and qualitative antibody responses to the colonizing-serotype.
authors.affiliation: University of the Witwatersrand, Department of Science and Technology/National Research Foundation: Vaccine Preventable Diseases & Respiratory and Meningeal Pathogens Research Unit, Johannesburg, South Africa. shabirm@nicd.ac.za
authors.forename: Shabir A
authors.initials: SA
authors.lastname: Madhi
authors.forename: Avy
authors.initials: A
authors.lastname: Violari
authors.forename: Keith P
authors.initials: KP
authors.lastname: Klugman
authors.forename: Gina
authors.initials: G
authors.lastname: Lin
authors.forename: James A
authors.initials: JA
authors.lastname: McIntyre
authors.forename: Anne
authors.initials: A
authors.lastname: von Gottberg
authors.forename: Patrick
authors.initials: P
authors.lastname: Jean-Philippe
authors.forename: Mark F
authors.initials: MF
authors.lastname: Cotton
authors.forename: Peter
authors.initials: P
authors.lastname: Adrian
mesh_terms: D000907:Antibodies, Bacterial / Q000096:biosynthesis / Q000276:immunology*; D015658:HIV Infections / Q000188:drug therapy / Q000276:immunology / Q000382:microbiology; D006801:Humans; D007114:Immunization / Q000379:methods; D007223:Infant; D009305:Nasopharynx / Q000276:immunology / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000276:immunology* / Q000517:prevention & control* / Q000821:virology; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology*; D012703:Serotyping / Q000379:methods; D013296:Streptococcus pneumoniae / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
chemical_list: D000907:Antibodies, Bacterial; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate