title: Evaluation of the indirect effects of a pneumococcal vaccine in a community-randomized study.
abstract: When a sufficiently high proportion of a population is immunized with a vaccine, reduction in secondary transmission of disease can confer significant protection to unimmunized population members. We propose a straightforward method to estimate the degree of this indirect effect of vaccination in the context of a community-randomized vaccine trial. A conditional logistic regression model that accounts for within-randomization unit correlation over time is described, which models risk of disease as a function of community-level covariates. The approach is applied to an example data set from a pneumococcal conjugate vaccine study, with study arm and immunization levels forming the covariates of interest for the investigation of indirect effects.
authors.affiliation: Center for American Indian Health, Department of International Health, The Johns Hopkins Bloomberg School of Public Health, Baltimore, MD 21205, USA. LMoulton@jhsph.edu
authors.forename: L H
authors.initials: LH
authors.lastname: Moulton
authors.forename: K L
authors.initials: KL
authors.lastname: O'Brien
authors.forename: R
authors.initials: R
authors.lastname: Reid
authors.forename: R
authors.initials: R
authors.lastname: Weatherholtz
authors.forename: M
authors.initials: M
authors.lastname: Santosham
authors.forename: G R
authors.initials: GR
authors.lastname: Siber
mesh_terms: D002675:Child, Preschool; D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D006801:Humans; D007223:Infant; D016015:Logistic Models; D022401:Meningococcal Vaccines / Q000276:immunology / Q000627:therapeutic use; D011008:Pneumococcal Infections / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control*; D022242:Pneumococcal Vaccines / Q000276:immunology / Q000627:therapeutic use*; D014481:United States; D016549:United States Indian Health Service; D018074:Vaccines, Conjugate / Q000276:immunology / Q000627:therapeutic use
chemical_list: D000069443:Heptavalent Pneumococcal Conjugate Vaccine; D022401:Meningococcal Vaccines; D022242:Pneumococcal Vaccines; D018074:Vaccines, Conjugate