title: The safety of immunizing with tetanus-diphtheria-acellular pertussis vaccine (Tdap) less than 2 years following previous tetanus vaccination: Experience during a mass vaccination campaign of healthcare personnel during a respiratory illness outbreak.
abstract: BACKGROUND
  Tdap is recommended for health care personnel (HCP) aged <65 years who received tetanus diphtheria or tetanus toxoid immunization (Td/TT) ≥2 years earlier. During a medical center Tdap vaccination campaign, we assessed the safety of use of a Td/TT to Tdap interval <2 years in HCP. We also describe reactogenicity in HCP who were aged ≥65 years or pregnant.
  
  
  METHODS
  HCP vaccinated with Tdap were surveyed to assess time since last Td/TT (≥2 years vs. <2 years), age, pregnancy status, and injection site adverse events (AEs) during the 2 weeks after Tdap. AE rates were calculated and compared by non-inferiority analysis using a predetermined margin of 10%. We searched clinic logbooks to assess for clinically important adverse events during the 2 months after Tdap.
  
  
  RESULTS
  Of the 4524 vaccinated HCP, 2221 (49.1%) completed a safety survey which met criteria for analysis. Non-inferiority analysis found that rates of moderate and/or severe injection site AEs were not significantly greater in those vaccinated <2 years than in those vaccinated ≥2 years after previous Td/TT. Three serious adverse events were reported during the 2 months after vaccination, none in persons who were ≥65 years, pregnant or received Td/TT <2 years before.
  
  
  CONCLUSIONS
  Our findings add to the body of evidence that a short interval between Td/TT and a single dose of Tdap is safe.
authors.affiliation: Dartmouth Medical School, Hanover, NH, USA. elizabeth.talbot@dartmouth.edu
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Talbot
authors.forename: Kristin H
authors.initials: KH
authors.lastname: Brown
authors.forename: Kathryn B
authors.initials: KB
authors.lastname: Kirkland
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Baughman
authors.forename: Scott A
authors.initials: SA
authors.lastname: Halperin
authors.forename: Karen R
authors.initials: KR
authors.lastname: Broder
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D022422:Diphtheria-Tetanus Vaccine / Q000008:administration & dosage; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage / Q000009:adverse effects*; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006282:Health Personnel / Q000706:statistics & numerical data*; D006306:Health Surveys; D006801:Humans; D007115:Immunization Schedule; D008297:Male; D032541:Mass Vaccination; D008875:Middle Aged; D011247:Pregnancy; D013745:Tetanus Toxoid / Q000008:administration & dosage; D013997:Time Factors; D014917:Whooping Cough / Q000517:prevention & control; D055815:Young Adult
chemical_list: D022422:Diphtheria-Tetanus Vaccine; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines; D013745:Tetanus Toxoid