title: Time Until Emergence of HIV Test Reactivity Following Infection With HIV-1: Implications for Interpreting Test Results and Retesting After Exposure.
abstract: BACKGROUND
  Understanding the period of time between an exposure resulting in infection with human immunodeficiency virus (HIV) and when a test can reliably detect the presence of that infection, that is, the test window period, may benefit testing programs and clinicians in counseling patients about when the clinician and the patient can be confident a suspected exposure did not result in HIV infection.
  
  
  METHODS
  We evaluated the intervals between reactivity of the Aptima HIV-1 RNA test (Aptima) and 20 US Food and Drug Administration-approved HIV immunoassays using 222 longitudinally collected plasma specimens from HIV-1 seroconverters from the United States. Using interval-censored survival and binomial regression approaches a multi-model framework was implemented to estimate the relative emergence of test reactivity, referred to here as an inter-test reactivity interval (ITRI). We then combined ITRI results with simulated data for the eclipse period, the time between exposure and detection of HIV virus by Aptima, to estimate the window period for each test.
  
  
  RESULTS
  The estimated ITRIs were shorter with each new class of HIV tests, ranging from 5.9 to 24.8 days. The 99thpercentiles of the window period probability distribution ranged from 44 days for laboratory screening tests that detect both antigen and antibody to 65 days for the Western blot test.
  
  
  CONCLUSIONS
  Our directly comparable estimates of the emergence of reactivity for 20 immunoassays are valuable to testing providers for interpreting negative HIV test results obtained shortly after exposure, and for counseling individuals on when to retest after an exposure.
authors.affiliation: Division of HIV/AIDS Prevention.
authors.forename: Kevin P
authors.initials: KP
authors.lastname: Delaney
authors.affiliation: Division of HIV/AIDS Prevention.
authors.forename: Debra L
authors.initials: DL
authors.lastname: Hanson
authors.affiliation: Division of HIV/AIDS Prevention.
authors.forename: Silvina
authors.initials: S
authors.lastname: Masciotra
authors.affiliation: Division of HIV/AIDS Prevention.
authors.forename: Steven F
authors.initials: SF
authors.lastname: Ethridge
authors.affiliation: Division of HIV/AIDS Prevention.
authors.forename: Laura
authors.initials: L
authors.lastname: Wesolowski
authors.affiliation: Office of the Director, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, Georgia.
authors.forename: Sherry Michele
authors.initials: SM
authors.lastname: Owen
mesh_terms: D005260:Female; D015658:HIV Infections / Q000175:diagnosis* / Q000821:virology*; D006679:HIV Seropositivity; D015497:HIV-1 / Q000145:classification / Q000235:genetics*; D015498:HIV-2 / Q000145:classification / Q000235:genetics; D006801:Humans; D008297:Male; D025202:Molecular Diagnostic Techniques / Q000379:methods / Q000592:standards; D012367:RNA, Viral; D012680:Sensitivity and Specificity; D013997:Time Factors
chemical_list: D012367:RNA, Viral
keywords: HIV eclipse period; HIV immunoassays; RNA nucleic acid test; window period of infection