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Impact of conjugate 7-valent vaccination in Belgium: addressing methodological challenges

Germaine Hanquet1, Tinne Lernout, Anne Vergison

  • 1Scientific Institute of Public Health, Brussels, Belgium. germaine@skynet.be

Vaccine
|February 24, 2011
PubMed

Insights

The 7-valent pneumococcal conjugate vaccine (PCV7) significantly reduced vaccine-type invasive pneumococcal disease in young Belgian children. However, non-vaccine types increased, highlighting the need for ongoing surveillance and further research into serotype dynamics.

Area of Science:

  • Pediatric Infectious Diseases
  • Vaccinology
  • Epidemiology

Background:

  • The 7-valent pneumococcal conjugate vaccine (PCV7) was integrated into Belgium's national immunization program in 2007.
  • Pneumococcal invasive disease (PID) remains a significant public health concern, particularly in young children.

Purpose of the Study:

  • To evaluate the early impact of PCV7 introduction on the incidence of pediatric invasive pneumococcal disease in Belgium.
  • To assess changes in both vaccine-type and non-vaccine type pneumococcal serotypes following PCV7 implementation.

Main Methods:

  • Utilized national surveillance data to compare PID incidence rates before and after PCV7 introduction.
  • Analyzed serotype-specific incidence in children under two years of age.
  • Adjusted for under-reporting and pre-vaccination trends to estimate vaccine impact.

Main Results:

  • A 96% decline in vaccine-type serotype incidence was observed in children <2 years old.
  • A 2-3 fold increase in non-vaccine type serotypes was noted post-PCV7 introduction.
  • Overall invasive pneumococcal disease incidence decreased by 23-46%, with adjustments for reporting and trends.

Conclusions:

  • PCV7 demonstrated substantial early success in reducing vaccine-type invasive pneumococcal disease in young children.
  • The rise in non-vaccine type serotypes, including types 1 and 19A which increased pre-vaccination, necessitates continued serotype surveillance.
  • Accurate estimation of vaccine impact requires adjustment for pre-existing trends and thorough exploration of serotype dynamics.

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