title: Choice of measures of vaccination and estimates of risk of pediatric pertussis.
abstract: BACKGROUND
  Vaccination uptake at the individual level can be assessed in a variety of ways, including traditional measures of being up-to-date (UTD), measures of UTD that consider dose timing, like age-appropriate vaccination, and risk reduction from individual doses. This analysis compared methods of operationalizing vaccination uptake and corresponding risk of pertussis infection.
  
  
  METHODS
  City-wide case-control study of children in Philadelphia aged 3 months through 6 years, between 2001 and 2013. Multiple logistic regression was used to isolate the independent effects of each measure of vaccination uptake and the corresponding relative odds of pertussis.
  
  
  RESULTS
  Being UTD on vaccinations was associated with a 52% reduction in risk of pertussis (OR 0.48, 95% CI: 0.34, 0.69). Evaluation of delayed receipt of vaccine versus on-time UTD yielded similar results. There was a decrease in risk of pertussis for each additional dose received with the greatest reduction in pertussis infection observed from the first (OR 0.48, 95% CI: 0.28, 0.83) and second dose (OR 0.17, 95% CI: 0.08, 0.34). Additional doses conferred minimal additional protection in this age group.
  
  
  CONCLUSIONS
  Examining vaccination status by individual doses may offer improved predictive capacity for identifying children at risk for pertussis infection compared to the traditional UTD measure.
authors.affiliation: Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Philadelphia, PA 19104, United States. Electronic address: ng338@drexel.edu.
authors.forename: Neal D
authors.initials: ND
authors.lastname: Goldstein
authors.affiliation: Division of Disease Control, Philadelphia Department of Public Health, Philadelphia, PA 19146, United States.
authors.forename: E Claire
authors.initials: EC
authors.lastname: Newbern
authors.affiliation: Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Philadelphia, PA 19104, United States.
authors.forename: Alison A
authors.initials: AA
authors.lastname: Evans
authors.affiliation: Division of Disease Control, Philadelphia Department of Public Health, Philadelphia, PA 19146, United States.
authors.forename: Kate
authors.initials: K
authors.lastname: Drezner
authors.affiliation: Department of Epidemiology and Biostatistics, Drexel University School of Public Health, Philadelphia, PA 19104, United States.
authors.forename: Seth L
authors.initials: SL
authors.lastname: Welles
mesh_terms: D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D004363:Drug Utilization; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010567:Pertussis Vaccine / Q000008:administration & dosage*; D015143:Philadelphia / Q000453:epidemiology; D018570:Risk Assessment; D014917:Whooping Cough / Q000453:epidemiology* / Q000517:prevention & control*
chemical_list: D010567:Pertussis Vaccine
keywords: Bordatella pertussis; DTaP; Immunization; Pediatric; Whooping cough