title: Impact and cost-effectiveness of a second tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine dose to prevent pertussis in the United States.
abstract: BACKGROUND
  The United States experienced a substantial increase in reported pertussis cases over the last decade. Since 2005, persons 11 years and older have been routinely recommended to receive a single dose of tetanus toxoid, reduced diphtheria toxoid and acellular pertussis (Tdap) vaccine. The objective of this analysis was to evaluate the potential impact and cost-effectiveness of recommending a second dose of Tdap.
  
  
  METHODS
  A static cohort model was used to calculate the epidemiologic and economic impact of adding a second dose of Tdap at age 16 or 21 years. Projected costs and outcomes were examined from a societal perspective over a 20-year period. Quality-adjusted Life Years (QALY) saved were calculated.
  
  
  RESULTS
  Using baseline pertussis incidence from the National Notifiable Diseases Surveillance System, Tdap revaccination at either age 16 or 21 years would reduce outpatient visits by 433 (5%) and 285 (4%), and hospitalization cases by 7 (7%) and 5 (5%), respectively. The costs per QALY saved with a second dose of Tdap were approximately US $19.7 million (16 years) and $26.2 million (21 years). In sensitivity analyses, incidence most influenced the model; as incidence increased, the costs per QALY decreased. To a lesser degree, initial vaccine effectiveness and waning of effectiveness also affected cost outcomes. Multivariate sensitivity analyses showed that under a set of optimistic assumptions, the cost per QALY saved would be approximately $163,361 (16 years) and $204,556 (21 years).
  
  
  CONCLUSIONS
  A second dose of Tdap resulted in a slight decrease in the number of cases and other outcomes, and that trend is more apparent when revaccinating at age 16 years than at age 21 years. Both revaccination strategies had high dollar per QALY saved even under optimistic assumptions in a multivariate sensitivity analysis.
authors.affiliation: Epidemic Intelligence Service, Division of Scientific Education and Professional Development, Center for Surveillance, Epidemiology and Laboratory Services, Centers for Disease Control and Prevention, 1600 Clifton Rd, N.E., Atlanta, GA 30329-4027, United States; Meningitis and Vaccine Preventable Disease Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, N.E., Atlanta, GA 30329-4027, United States; National Institute of Infectious Diseases, 1-23-1 Toyama, Shinjyuku-ku, Tokyo 162-8640, Japan. Electronic address: hakamiya@nih.go.jp.
authors.forename: Hajime
authors.initials: H
authors.lastname: Kamiya
authors.affiliation: Assessment Branch, Immunization Services Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, N.E., Atlanta, GA 30329-4027, United States.
authors.forename: Bo-Hyun
authors.initials: BH
authors.lastname: Cho
authors.affiliation: Assessment Branch, Immunization Services Division, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, N.E., Atlanta, GA 30329-4027, United States.
authors.forename: Mark L
authors.initials: ML
authors.lastname: Messonnier
authors.affiliation: Field Support Branch, Division of Reproductive Health, National Center For Chronic Disease Prevention & Health Promotion, Centers for Disease Control and Prevention, 1600 Clifton Rd, N.E., Atlanta, GA 30329-4027, United States.
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Clark
authors.affiliation: Meningitis and Vaccine Preventable Disease Branch, Division of Bacterial Diseases, National Center for Immunization and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Rd, N.E., Atlanta, GA 30329-4027, United States. Electronic address: JLiang@cdc.gov.
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Liang
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D003362:Cost-Benefit Analysis; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage* / Q000191:economics; D006801:Humans; D007117:Immunization, Secondary / Q000191:economics*; D008962:Models, Theoretical; D019057:Quality-Adjusted Life Years; D014481:United States; D014917:Whooping Cough / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines
keywords: Adolescent; Adult; Cost-effectiveness; Pertussis; Revaccination; Tdap