title: Seroconversion following nonoccupational postexposure prophylaxis against HIV.
abstract: BACKGROUND
  The efficacy of antiretroviral postexposure prophylaxis (PEP) against infection with human immunodeficiency virus (HIV) following occupational exposures has prompted the use of PEP after nonoccupational exposures. There are, however, important differences between occupational and nonoccupational exposures, and the effectiveness of PEP following nonoccupational exposure is unknown. We sought to describe the occurrence and circumstances of HIV seroconversion following nonoccupational PEP.
  
  
  METHODS
  HIV uninfected individuals reporting potential sexual or injection drug use exposures to HIV in the preceding 72 h received a 28-day regimen of antiretroviral therapy and counseling in a nonrandomized trial. The level of HIV antibody was measured 12 weeks after PEP initiation.
  
  
  RESULTS
  Of 877 exposed subjects, 702 were evaluable 12 weeks after exposure. Seroconversion was detected in 7 subjects (1%; 95% confidence interval, 0.4%-2%). Three seroconverters reported having no exposures after PEP initiation and, thus, probably represent evidence of chemoprophylactic failure. In the other 4 subjects, additional exposures to HIV after PEP initiation or detection of HIV RNA in plasma specimens obtained at baseline precluded determination of the source of seroconversion. No exposure source was available to assess genetic concordance with the seroconverter's virus.
  
  
  CONCLUSIONS
  As for occupational exposure, PEP is not completely effective in preventing HIV infection following nonoccupational exposure. Therefore, primary prevention remains essential. In contrast to the occupational setting, the potential source of exposure is rarely available for testing in the nonoccupational setting, and exposures are often not isolated. Thus, it is often impossible to determine whether seroconversion resulted from failure of PEP or from other exposures, posing difficulties for future comparative studies seeking to evaluate the effectiveness of PEP.
authors.affiliation: Positive Health Program at San Francisco General Hospital, California, USA. mroland@php.ucsf.edu
authors.forename: Michelle E
authors.initials: ME
authors.lastname: Roland
authors.forename: Torsten B
authors.initials: TB
authors.lastname: Neilands
authors.forename: Melissa R
authors.initials: MR
authors.lastname: Krone
authors.forename: Mitchell H
authors.initials: MH
authors.lastname: Katz
authors.forename: Karena
authors.initials: K
authors.lastname: Franses
authors.forename: Robert M
authors.initials: RM
authors.lastname: Grant
authors.forename: Michael P
authors.initials: MP
authors.lastname: Busch
authors.forename: Frederick M
authors.initials: FM
authors.lastname: Hecht
authors.forename: Barbara L
authors.initials: BL
authors.lastname: Shacklett
authors.forename: James O
authors.initials: JO
authors.lastname: Kahn
authors.forename: Joshua D
authors.initials: JD
authors.lastname: Bamberger
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Coates
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Chesney
authors.forename: Jeffrey N
authors.initials: JN
authors.lastname: Martin
mesh_terms: D019380:Anti-HIV Agents / Q000008:administration & dosage* / Q000627:therapeutic use*; D003376:Counseling; D005260:Female; D015483:HIV Antibodies / Q000097:blood; D015658:HIV Infections / Q000209:etiology / Q000517:prevention & control*; D006679:HIV Seropositivity; D006266:Health Education; D006801:Humans; D008297:Male; D016485:Needle Sharing / Q000009:adverse effects; D012309:Risk-Taking; D012725:Sexual Behavior; D015819:Substance Abuse, Intravenous / Q000150:complications
chemical_list: D019380:Anti-HIV Agents; D015483:HIV Antibodies