title: Immune responses in adults to revaccination with a tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine 10 years after a previous dose.
abstract: BACKGROUND
  Although decennial adult boosters of tetanus and diphtheria toxoids are recommended in Canada and the United States, a second dose of pertussis vaccine during adulthood is not currently recommended.
  
  
  METHODS
  This open-label, multicenter study compared the safety and immunogenicity of a first dose of an adult formulation of tetanus, diphtheria, and acelluar pertussis vaccine (Tdap) with a repeat dose of Tdap in adults who had received Tdap 10 years previously.
  
  
  RESULTS
  A total of 769 participants ranging in age from 20 to 72 years took part in this study; 92.3% of naïve and 92.7% of repeat-dose participants had at least one solicited adverse event. Injection-site pain (84.4% and 87.8%), erythema (29.7% and 23.1%), and swelling (23.3% and 20.5%), and myalgia (53.5% and 60.1%), headache (37.6% and 40.6%), malaise (29.0% and 29.4%), and fever (4.9% and 4.2%) were the most common solicited adverse events reported in the naïve and repeat-dose groups, respectively. Postvaccination antibody levels ≥0.1 IU/mL were achieved by 99.7% of the naïve-group participants and all of the repeat-dose participants for tetanus and 96.1% of the naïve group and 98.5% of the repeat-dose group for diphtheria, both meeting the predefined noninferiority criteria. For pertussis antibodies, anti-PT (89.2 EU/mL vs. 116 EU/mL) was higher in the repeat-dose group, anti-FHA (249 vs. 214) and anti-PRN (216 vs. 266) were similar, and anti-FIM (1015 vs. 779) was higher in the naïve group. Noninferiority criteria were met for all antigens except for anti-FIM.
  
  
  CONCLUSIONS
  A repeat dose of Tdap vaccine 10 years after the first dose was well tolerated and immunogenic in adults (ClinicalTrials.gov identifier: NCT00712959).
authors: Canadian Center for Vaccinology, Dalhousie University, IWK Health Centre, and Capital Health, Halifax, NS, Canada. scott.halperin@dal.ca
authors: Scott A
authors: SA
authors: Halperin
authors: David
authors: D
authors: Scheifele
authors: Gaston
authors: G
authors: De Serres
authors: Francisco
authors: F
authors: Noya
authors: William
authors: W
authors: Meekison
authors: Paul
authors: P
authors: Zickler
authors: Luc
authors: L
authors: Larrivée
authors: Joanne M
authors: JM
authors: Langley
authors: Shelly A
authors: SA
authors: McNeil
authors: Simon
authors: S
authors: Dobson
authors: Emilia
authors: E
authors: Jordanov
authors: Manoj
authors: M
authors: Thakur
authors: Michael D
authors: MD
authors: Decker
authors: David R
authors: DR
authors: Johnson
mesh_terms: D000328:Adult; D000368:Aged; D000907:Antibodies, Bacterial / Q000097:blood*; D000992:Antitoxins / Q000097:blood*; D002170:Canada; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage* / Q000009:adverse effects / Q000276:immunology*; D005260:Female; D006801:Humans; D007117:Immunization, Secondary / Q000009:adverse effects / Q000379:methods*; D008297:Male; D008875:Middle Aged; D014481:United States
chemical_list: D000907:Antibodies, Bacterial; D000992:Antitoxins; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines