Immunity to cross-reactive serotypes induced by pneumococcal conjugate vaccines in infants

J Infect Dis. 1999 Nov;180(5):1569-76. doi: 10.1086/315096.


Infants were immunized with 1 of the 3 experimental pneumococcal conjugate vaccines that contain 6B and 19F but not 6A or 19A serotypes. Their sera were studied for the capacity to opsonize Streptococcus pneumoniae 6A, 6B, 19A, and 19F serotypes and the level of IgG antibody to the 4 serotypes. Significant increases were observed in the number of infants with detectable opsonophagocytic titers with 3 conjugate vaccines for 6B (vaccine) serotype but with only 2 vaccines for 6A (cross-reactive) serotype. Significant increases were observed with 2 conjugate vaccines for 19F serotype but with only 1 vaccine for 19A serotype. Thus, some conjugate vaccines may elicit cross-protection better than others. In addition, correlations between opsonophagocytic titers and IgG antibody levels by ELISA were high for 6B and 19F serotypes but low for 6A and 19A serotypes. Thus, ELISA may be an inadequate surrogate assay of vaccine response for cross-reactive serotypes.

Publication types

  • Clinical Trial
  • Controlled Clinical Trial
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adult
  • Antibodies, Bacterial / blood*
  • Bacterial Vaccines / immunology*
  • Carbohydrate Sequence
  • Cross Reactions
  • Enzyme-Linked Immunosorbent Assay
  • Humans
  • Immunoglobulin G / blood
  • Infant
  • Molecular Sequence Data
  • Opsonin Proteins / immunology*
  • Phagocytosis
  • Pneumococcal Infections / immunology
  • Pneumococcal Infections / prevention & control
  • Serotyping
  • Streptococcus pneumoniae / classification
  • Streptococcus pneumoniae / immunology*
  • Vaccination
  • Vaccines, Conjugate / immunology*


  • Antibodies, Bacterial
  • Bacterial Vaccines
  • Immunoglobulin G
  • Opsonin Proteins
  • Vaccines, Conjugate