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J Infect Dis. 2005 Aug 1;192(3):367-76. Epub 2005 Jun 28.

Serum serotype-specific pneumococcal anticapsular immunoglobulin g concentrations after immunization with a 9-valent conjugate pneumococcal vaccine correlate with nasopharyngeal acquisition of pneumococcus.

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Pediatric Infectious Disease Unit, Soroka University Medical Center and the Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.



Immunization with pneumococcal conjugate vaccines (PCVs) reduces nasopharyngeal colonization by Streptococcus pneumoniae. We attempted to correlate postvaccination serum serotype-specific pneumococcal anticapsular immunoglobulin (Ig) G concentrations with new acquisitions of vaccine-type (VT) serotypes and the VT-related serotype 6A.


A total of 132 day care center attendees aged 12-35 months received a 9-valent PCV (PnCRM9) and were followed for 2 years for new nasopharyngeal acquisitions of S. pneumoniae. A total of 132 control subjects received a meningococcus type C conjugate vaccine. Serum serotype-specific pneumococcal anticapsular IgG concentrations were determined at 1 month after complete immunization.


A logistic regression model of the probability of having a new acquisition of S. pneumoniae (for serotypes 9V, 14, 19F, and 23F) as a function of the IgG concentration showed a negative coefficient, indicating that higher IgG concentrations led to a decreasing probability of having a new acquisition, and achieved statistical significance for serotypes 14 and 19F. Similarly, a new acquisition of serotype 6A was shown to be significantly inversely related to the anti-6B IgG concentration. An effect of the IgG concentration on duration of carriage was not demonstrated.


The magnitude of herd protection against S. pneumoniae provided by a PCV may depend on the magnitude of IgG concentrations.

[Indexed for MEDLINE]

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