title: Immunogenicity of seven-valent pneumococcal conjugate vaccine administered at 6, 14 and 40 weeks of age in South African infants.
abstract: BACKGROUND
  The high cost of pneumococcal conjugate vaccine (PCV) and local epidemiological factors contributed to evaluating different PCV dosing-schedules. This study evaluated the immunogenicity of seven-valent PCV (PCV7) administered at 6-weeks; 14-weeks and 9-months of age.
  
  
  METHODS
  250 healthy, HIV-unexposed infants were immunized with PCV7 concurrently with other childhood vaccines. Serotype-specific anti-capsular IgG concentrations were measured one-month following the 1(st) and 2(nd) PCV-doses, prior to and two-weeks following the 3(rd) dose. Opsonophagocytic killing assay (OPA) was measured for three serotypes following the 2(nd) and 3(rd) PCV7-doses. Immunogenicity of the current schedule was compared to a historical cohort of infants who received PCV7 at 6, 10 and 14 weeks of age.
  
  
  RESULTS
  The proportion of infants with serotype-specific antibody ≥ 0.35 µg/ml following the 2(nd) PCV7-dose ranged from 84% for 6B to ≥ 89% for other serotypes. Robust antibody responses were observed following the 3(rd) dose. The proportion of children with OPA ≥ 8 for serotypes 9V, 19F and 23F increased significantly following the 3(rd) PCV7-dose to 93.6%; 86.0% and 89.7% respectively. The quantitative antibody concentrations following the 2(nd) PCV7-dose were comparable to that after the 3(rd) -dose in the 6-10-14 week schedule. Geometric mean concentrations (GMCs) following the 3(rd) PCV7-dose were higher for all serotypes in this study compared to the historical cohort.
  
  
  CONCLUSIONS
  The studied PCV7 dosing schedule induced good immune responses, including higher GMCs following the 3(rd-)dose at 9-months compared to when given at 14-weeks of age. This may confer longer persistence of antibodies and duration of protection against pneumococcal disease.
authors.affiliation: Department of Science/National Research Foundation: Vaccine Preventable Diseases, University of the Witwatersrand, Faculty of Health Science, Johannesburg, South Africa ; Medical Research Council, Respiratory and Meningeal Pathogens Research Unit, Johannesburg, South Africa.
authors.forename: Stephanie A
authors.initials: SA
authors.lastname: Jones
authors.forename: Michelle
authors.initials: M
authors.lastname: Groome
authors.forename: Anthonet
authors.initials: A
authors.lastname: Koen
authors.forename: Nadia
authors.initials: N
authors.lastname: Van Niekerk
authors.forename: Poonam
authors.initials: P
authors.lastname: Sewraj
authors.forename: Locadiah
authors.initials: L
authors.lastname: Kuwanda
authors.forename: Alane
authors.initials: A
authors.lastname: Izu
authors.forename: Peter V
authors.initials: PV
authors.lastname: Adrian
authors.forename: Shabir A
authors.initials: SA
authors.lastname: Madhi
mesh_terms: D000328:Adult; D000367:Age Factors; D000907:Antibodies, Bacterial / Q000097:blood* / Q000276:immunology; D000917:Antibody Formation / Q000187:drug effects* / Q000276:immunology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D011008:Pneumococcal Infections / Q000097:blood* / Q000276:immunology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000008:administration & dosage* / Q000276:immunology; D012189:Retrospective Studies; D013019:South Africa; D013997:Time Factors
chemical_list: D000907:Antibodies, Bacterial; D022242:Pneumococcal Vaccines