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Original Investigation
July 12, 2016

Sexual Activity Without Condoms and Risk of HIV Transmission in Serodifferent Couples When the HIV-Positive Partner Is Using Suppressive Antiretroviral Therapy

Author Affiliations
  • 1Research Department of Infection and Population Health, University College London, London, United Kingdom
  • 2Department of Infectious Diseases/CHIP, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
  • 3Division of Infectious Diseases and Hospital Epidemiology, Cantonal Hospital, St Gallen, Switzerland
  • 4HIV i-Base, London, United Kingdom
  • 5University Medical Center Hamburg-Eppendorf, Hamburg-Eppendorf, Germany
  • 6European AIDS Treatment Group, Bruxelles, Belgium
  • 7Hospital Clinico San Carlos and Universidad Complutense, Madrid, Spain
  • 8Institute of Infection and Global Health, University of Liverpool, Liverpool, United Kingdom
  • 9Chelsea and Westminster NHS Foundation Trust, London, United Kingdom
  • 10Hospital Virgen del Rocío, Sevilla, Spain
  • 11Hospital General de Elche & Universidad Miguel Hernández, Alicante, Spain
  • 12IrsiCaixa Foundation, UAB, UVIC-UCC, Hospital Universitari “Germans Trias i Pujol,” Badalona, Catalonia, Spain
  • 13Department of Public Health, Nice University Hospital and EA 6312, University Nice Sophia-Antipolis, France
  • 14Rigshospitalet, Copenhagen, Denmark
  • 15Division of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland
  • 16Unit of Infectious Diseases and Dermatology, Department of Medicine, Karolinska Institutet, and Department of Infectious Diseases, Karolinska University Hospital, Stockholm, Sweden
  • 17Department of Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland
  • 18Academic Medical Center, Amsterdam, the Netherlands
  • 19Medical University of Vienna, Vienna, Austria
  • 20Division of Infectious Diseases and Hospital Epidemiology, University Hospital Basel, Basel, Switzerland
  • 21Department of Internal Medicine 1, University Hospital of Cologne, Cologne, Germany
  • 22Ospedal San Paolo, Milan, Italy
  • 23Ospedale L. Spallanzani, Roma, Italy
  • 24Praxis Driesener Straße, Berlin, Germany
  • 25Helsinki University Central Hospital, Helsinki, Finland
  • 26Medical University Innsbruck, Innsbruck, Austria
  • 27Hvidovre Universitets Hospital, Hvidovre, Denamrk
  • 28Hospital Clínico Universitario de Santiago de Compostela, Santiago de Compostela, Spain
  • 29Coventry and Warwickshire Hospital, Coventry, United Kingdom
JAMA. 2016;316(2):171-181. doi:10.1001/jama.2016.5148
Key Points

Question  What is the risk of HIV transmission through condomless sex from an HIV-positive person taking suppressive ART?

Findings  In this observational study in HIV-serodifferent heterosexual and MSM couples having ongoing condomless sex over 1238 couple-years of follow-up, there were no cases of within-couple HIV transmission (upper 95% confidence limit of 0.30/100 couple-years of follow-up).

Meaning  This study provides estimates of the risk of HIV transmission through condomless anal and vaginal sex with use of suppressive ART.


Importance  A key factor in assessing the effectiveness and cost-effectiveness of antiretroviral therapy (ART) as a prevention strategy is the absolute risk of HIV transmission through condomless sex with suppressed HIV-1 RNA viral load for both anal and vaginal sex.

Objective  To evaluate the rate of within-couple HIV transmission (heterosexual and men who have sex with men [MSM]) during periods of sex without condoms and when the HIV-positive partner had HIV-1 RNA load less than 200 copies/mL.

Design, Setting, and Participants  The prospective, observational PARTNER (Partners of People on ART—A New Evaluation of the Risks) study was conducted at 75 clinical sites in 14 European countries and enrolled 1166 HIV serodifferent couples (HIV-positive partner taking suppressive ART) who reported condomless sex (September 2010 to May 2014). Eligibility criteria for inclusion of couple-years of follow-up were condomless sex and HIV-1 RNA load less than 200 copies/mL. Anonymized phylogenetic analysis compared couples’ HIV-1 polymerase and envelope sequences if an HIV-negative partner became infected to determine phylogenetically linked transmissions.

Exposures  Condomless sexual activity with an HIV-positive partner taking virally suppressive ART.

Main Outcomes and Measures  Risk of within-couple HIV transmission to the HIV-negative partner

Results  Among 1166 enrolled couples, 888 (mean age, 42 years [IQR, 35-48]; 548 heterosexual [61.7%] and 340 MSM [38.3%]) provided 1238 eligible couple-years of follow-up (median follow-up, 1.3 years [IQR, 0.8-2.0]). At baseline, couples reported condomless sex for a median of 2 years (IQR, 0.5-6.3). Condomless sex with other partners was reported by 108 HIV-negative MSM (33%) and 21 heterosexuals (4%). During follow-up, couples reported condomless sex a median of 37 times per year (IQR, 15-71), with MSM couples reporting approximately 22 000 condomless sex acts and heterosexuals approximately 36 000. Although 11 HIV-negative partners became HIV-positive (10 MSM; 1 heterosexual; 8 reported condomless sex with other partners), no phylogenetically linked transmissions occurred over eligible couple-years of follow-up, giving a rate of within-couple HIV transmission of zero, with an upper 95% confidence limit of 0.30/100 couple-years of follow-up. The upper 95% confidence limit for condomless anal sex was 0.71 per 100 couple-years of follow-up.

Conclusions and Relevance  Among serodifferent heterosexual and MSM couples in which the HIV-positive partner was using suppressive ART and who reported condomless sex, during median follow-up of 1.3 years per couple, there were no documented cases of within-couple HIV transmission (upper 95% confidence limit, 0.30/100 couple-years of follow-up). Additional longer-term follow-up is necessary to provide more precise estimates of risk.