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Induction of immunologic memory by conjugated vs plain meningococcal C polysaccharide vaccine in toddlers: a

N E MacDonald1, S A Halperin, B J Law

  • 1University of Ottawa, Ontario, Canada. macdonaldvn@cheo.on.ca

JAMA
|December 1, 1998
PubMed

Insights

Meningococcal C conjugate vaccine is more effective in toddlers than polysaccharide vaccine, inducing better antibody responses and immunologic memory. This conjugate vaccine overcomes poor responses seen with older vaccines in young children.

Area of Science:

  • Immunology
  • Vaccinology
  • Pediatric Infectious Diseases

Background:

  • Meningococcal polysaccharide vaccines elicit poor immune responses in infants and toddlers.
  • Invasive meningococcal disease poses a high risk to these age groups.
  • Meningococcal C conjugate vaccines present a potential solution to overcome poor immunogenicity.

Purpose of the Study:

  • To evaluate the immunogenicity of meningococcal C conjugate vaccine in toddlers.
  • To assess the induction of immunologic memory following vaccination in toddlers.

Main Methods:

  • A multicenter, randomized, observer-blinded controlled trial involving 211 healthy toddlers (15-23 months).
  • Participants received two doses of meningococcal C conjugate vaccine, plain meningococcal polysaccharide vaccine, or hepatitis B virus vaccine, followed by a booster dose 12 months later.
  • Outcomes measured included IgG anticapsular antibody concentrations and complement-mediated bactericidal antibody levels.

Main Results:

  • Meningococcal C conjugate vaccine induced significantly higher IgG responses compared to polysaccharide vaccine after both doses.
  • Elevated antibody titers persisted for at least 12 months in the conjugate vaccine group.
  • The conjugate vaccine primed toddlers demonstrated a robust booster response to polysaccharide vaccine, while polysaccharide priming led to hyporesponsiveness.

Conclusions:

  • Meningococcal C conjugate vaccine is highly immunogenic in toddlers, inducing significant antibody titers and immunologic memory.
  • The conjugate vaccine overcomes the limitations of polysaccharide vaccines in this age group.
  • Polysaccharide vaccines are less effective and may induce a hyporesponsive state in toddlers.
Abstract

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