title: A comparison of 2 strategies to prevent infection following pertussis exposure in vaccinated healthcare personnel.
abstract: BACKGROUND
  Antibiotic postexposure prophylaxis (PEP) following pertussis exposure is recommended but has never been evaluated in healthcare personnel (HCP) vaccinated with acellular pertussis vaccine (Tdap).
  
  
  METHODS
  Tdap-vaccinated HCP were randomized to receive azithromycin PEP or no PEP following pertussis exposure. Acute and convalescent nasopharyngeal swabs and sera were obtained for pertussis testing by polymerase chain reaction (PCR) and anti-pertussis toxin (PT) immunoglobulin G, respectively. A nasopharyngeal aspirate was also collected for PCR and culture from subjects who reported respiratory symptoms within 21 days following identification of the exposure. Pertussis infection was defined as a positive culture or PCR, a 2-fold rise in anti-PT titer, or a single anti-PT titer of ≥94 enzyme-linked immunosorbent assay units/mL. Daily symptom monitoring without PEP was considered noninferior to PEP after pertussis exposure if the lower limit of the 1-sided 95% confidence interval (CI) for the reduction in pertussis was greater than -7%.
  
  
  RESULTS
  During 30 months of study, 86 subjects were randomized following a pertussis exposure. Using the predefined definition of infection, pertussis infection did not develop in 41 (97.6%) of 42 subjects who received azithromycin PEP and 38 (86.4%) of 44 subjects who did not receive PEP (absolute risk difference, -11.3%; lower bound of the 1-sided 95% CI, -20.6%; P = .81). However, no subject developed symptomatic pertussis confirmed with culture or a specific PCR assay, and possibly no subject developed subclinical pertussis infection based upon additional serologic testing.
  
  
  CONCLUSIONS
  Using the predefined definition of pertussis infection, noninferiority for preventing pertussis following exposure was not demonstrated for daily symptom monitoring of Tdap-vaccinated HCP without PEP when compared with antibiotic PEP. However, the small number of exposed HCP warrants further study of this approach.
  
  
  BACKGROUND
  NCT00469274.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, Baylor College of Medicine, Houston, Texas 77030, USA. goins@bcm.edu
authors.forename: William P
authors.initials: WP
authors.lastname: Goins
authors.forename: Kathryn M
authors.initials: KM
authors.lastname: Edwards
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Vnencak-Jones
authors.forename: Michael T
authors.initials: MT
authors.lastname: Rock
authors.forename: Melanie
authors.initials: M
authors.lastname: Swift
authors.forename: Valerie
authors.initials: V
authors.lastname: Thayer
authors.forename: William
authors.initials: W
authors.lastname: Schaffner
authors.forename: Thomas R
authors.initials: TR
authors.lastname: Talbot
mesh_terms: D000293:Adolescent; D000328:Adult; D000900:Anti-Bacterial Agents / Q000008:administration & dosage; D019072:Antibiotic Prophylaxis / Q000379:methods*; D000907:Antibodies, Bacterial / Q000097:blood; D000992:Antitoxins / Q000097:blood; D017963:Azithromycin / Q000008:administration & dosage*; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines / Q000008:administration & dosage / Q000276:immunology*; D005260:Female; D006282:Health Personnel; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D008297:Male; D008875:Middle Aged; D009305:Nasopharynx / Q000382:microbiology; D016273:Occupational Exposure; D056990:Post-Exposure Prophylaxis / Q000379:methods*; D016896:Treatment Outcome; D014917:Whooping Cough / Q000517:prevention & control*; D055815:Young Adult
chemical_list: D000900:Anti-Bacterial Agents; D000907:Antibodies, Bacterial; D000992:Antitoxins; D022681:Diphtheria-Tetanus-acellular Pertussis Vaccines; D007074:Immunoglobulin G; D017963:Azithromycin