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PLoS One. 2013 Aug 28;8(8):e72794. doi: 10.1371/journal.pone.0072794. eCollection 2013.

Immunogenicity of seven-valent pneumococcal conjugate vaccine administered at 6, 14 and 40 weeks of age in South African infants.

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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.



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.


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.


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.


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.

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