The Efficacy and Duration of Protection of Pneumococcal Conjugate Vaccines Against Nasopharyngeal Carriage: A Meta-regression Model

Pediatr Infect Dis J. 2015 Aug;34(8):858-64. doi: 10.1097/INF.0000000000000717.


Background: Pneumococcal conjugate vaccines (PCVs) reduce disease largely through their impact on nasopharyngeal (NP) carriage acquisition of Streptococcus pneumoniae, a precondition for developing any form of pneumococcal disease. We aimed to estimate the vaccine efficacy (VEC) and duration of protection of PCVs against S. pneumoniae carriage acquisition through meta-regression models.

Methods: We identified intervention studies providing NP carriage estimates among vaccinated and unvaccinated children at any time after completion of a full vaccination schedule. We calculated VEC for PCV7 serotypes, grouped as well as individually, and explored cross-protective efficacy against 6A. Efficacy estimates over time were obtained using a Bayesian meta-logistic regression approach, with time since completion of vaccination as a covariate.

Results: We used data from 22 carriage surveys (15 independent studies) from 5 to 64 months after the last PCV dose, including 14,298 children. The aggregate VEC for all PCV7 serotypes 6 months after completion of the vaccination schedule was 57% (95% credible interval: 50-65%), varying by serotype from 38% (19F) to 80%. Our model provides evidence of sustained protection of PCVs for several years, with an aggregate VEC of 42% (95% credible interval: 19-54%) at 5 years, although the waning differed between serotypes. We also found evidence of cross-protection against 6A, with a VEC of 39% 6 months after a complete schedule, decreasing to 0 within 5 years postvaccination.

Conclusion: Our results suggest that PCVs confer reasonable protection against acquisition of pneumococcal carriage of the 7 studied serotypes, for several years after vaccination, albeit with differences across serotypes.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antibodies, Bacterial / blood
  • Antibodies, Bacterial / immunology
  • Carrier State / epidemiology
  • Carrier State / immunology*
  • Carrier State / microbiology
  • Carrier State / prevention & control
  • Child
  • Humans
  • Models, Biological
  • Models, Statistical*
  • Nasopharynx / microbiology*
  • Pneumococcal Infections / epidemiology
  • Pneumococcal Infections / immunology*
  • Pneumococcal Infections / microbiology
  • Pneumococcal Infections / prevention & control
  • Pneumococcal Vaccines / immunology*
  • Vaccines, Conjugate / immunology*


  • Antibodies, Bacterial
  • Pneumococcal Vaccines
  • Vaccines, Conjugate