Immunogenicity and boosting after a reduced number of doses of a pneumococcal conjugate vaccine in infants and toddlers

Pediatr Infect Dis J. 2006 Apr;25(4):312-9. doi: 10.1097/01.inf.0000207483.60267.e7.

Abstract

Background: The minimum number of doses of pneumococcal conjugate vaccine required for protection is not known. We studied the immunogenicity of a reduced schedule in infants and toddlers.

Methods: U.K. infants were given either 2 or 3 doses (at 2 and 4 or 2/3/4 months of age) of a 9-valent pneumococcal conjugate vaccine (9VPCV) followed by boosting at 12 months of age. In a separate study, toddlers (12 months) received 1 or 2 doses (2 months apart) of 9VPCV followed by pneumococcal polysaccharide vaccine at 18 months of age.

Results: For infants, serotype-specific IgG geometric mean concentrations were similar post-primary immunization between the groups with both showing avidity maturation and similar booster responses. For toddlers, the primary response to 4 of the 9 serotypes was lower in the 1- compared with the 2-dose group (type 6B, 0.77 versus 7.1; type 14, 4.67 versus 14.98; type 19F, 5.05 versus 7.75; type 23F, 2.48 versus 5.05), although for all serotypes booster responses were similar between groups, and the postprimary responses in the 1-dose group were at least as high as those after infant immunization.

Conclusions: The 2-dose infant priming schedule of 9VPCV is comparable with the 3-dose schedule and may thus be equally protective, whereas 1 dose in toddlers may suffice for a catch-up.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Bacterial / blood
  • Dose-Response Relationship, Immunologic
  • Humans
  • Immunization Schedule
  • Immunization, Secondary*
  • Immunoglobulin G / blood*
  • Infant
  • Pneumococcal Infections / prevention & control
  • Pneumococcal Vaccines / administration & dosage*
  • Pneumococcal Vaccines / immunology*
  • Serotyping
  • Streptococcus pneumoniae / classification
  • Streptococcus pneumoniae / immunology
  • Vaccines, Conjugate / administration & dosage*
  • Vaccines, Conjugate / immunology*

Substances

  • Antibodies, Bacterial
  • Immunoglobulin G
  • Pneumococcal Vaccines
  • Vaccines, Conjugate