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Effectiveness analyses may underestimate protection of infants after group C meningococcal immunization

David M Vu1, Dominic Kelly, Paul T Heath

  • 1Children's Hospital Oakland Research Institute, Oakland, CA 94609, USA.

The Journal of Infectious Diseases
|June 17, 2006
PubMed

Insights

Group C meningococcal conjugate vaccine immunity wanes over time. However, children immunized as infants or toddlers retain significant protection 2-3 years post-vaccination compared to unvaccinated children.

Area of Science:

  • Immunology
  • Vaccinology
  • Pediatrics

Background:

  • Group C meningococcal conjugate vaccine effectiveness wanes significantly within 1-4 years post-immunization in infants and toddlers.
  • Uncertainty exists regarding the long-term protection conferred by infant and toddler immunization schedules.

Purpose of the Study:

  • To assess the duration and level of immunity conferred by Group C meningococcal conjugate vaccines in children previously immunized as infants or toddlers.
  • To compare the immunogenicity and protective capacity of different infant and toddler immunization regimens.

Main Methods:

  • Serum bactericidal activity was measured using human complement.
  • Group C anticapsular antibody concentrations were determined via radioantigen binding assay.
  • Passive protection was evaluated using an infant rat bacteremia model.

Main Results:

  • Children immunized 2-3 years prior showed higher antibody levels and bactericidal activity than unimmunized controls.
  • Infant immunization resulted in a higher proportion of protective serum bactericidal activity titers (61%) compared to toddler immunization (24%).
  • No significant difference in passive protection was observed between the infant and toddler groups (50% vs. 41%).

Conclusions:

  • No evidence suggests lower immunity in children immunized as infants compared to toddlers.
  • Approximately 40%-50% of both immunized groups exhibited protective immunity 2-3 years post-vaccination, significantly exceeding unimmunized controls (<5%).
Abstract

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