title: The Efficacy and Duration of Protection of Pneumococcal Conjugate Vaccines Against Nasopharyngeal Carriage: A Meta-regression Model.
abstract: 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.
  
  
  CONCLUSIONS
  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.
authors.affiliation: From the *Centre for the Mathematical Modelling of Infectious Diseases, Department of Infectious Disease Epidemiology, London School of Hygiene and Tropical Medicine; †Clinical Trials Unit, London School of Hygiene and Tropical Medicine; and ‡Institute of Child Health, University College London, London, United Kingdom.
authors.forename: Olivier
authors.initials: O
authors.lastname: Le Polain De Waroux
authors.forename: Stefan
authors.initials: S
authors.lastname: Flasche
authors.forename: David
authors.initials: D
authors.lastname: Prieto-Merino
authors.forename: David
authors.initials: D
authors.lastname: Goldblatt
authors.forename: W John
authors.initials: WJ
authors.lastname: Edmunds
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood / Q000276:immunology; D002353:Carrier State / Q000453:epidemiology / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D002648:Child; D006801:Humans; D008954:Models, Biological; D015233:Models, Statistical; D009305:Nasopharynx / Q000382:microbiology*; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000276:immunology* / Q000382:microbiology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000276:immunology*; D018074:Vaccines, Conjugate / Q000276:immunology*
chemical_list: D000907:Antibodies, Bacterial; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate