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Lancet. 2019 Jun 15;393(10189):2428-2438. doi: 10.1016/S0140-6736(19)30418-0. Epub 2019 May 2.

Risk of HIV transmission through condomless sex in serodifferent gay couples with the HIV-positive partner taking suppressive antiretroviral therapy (PARTNER): final results of a multicentre, prospective, observational study.

Collaborators (153)

Coll P, Cobarsi P, Nieto A, Meulbroek M, Carrillo A, Saz J, Guerrero JDR, García MV, Gutiérrez F, Masiá M, Robledano C, Leon A, Leal L, Redondo EG, Estrada VP, Marquez R, Sandoval R, Viciana P, Espinosa N, Lopez-Cortes L, Podzamczer D, Tiraboschi J, Morenilla S, Antela A, Losada E, Nwokolo N, Sewell J, Clarke A, Kirk S, Knott A, Rodger AJ, Fernandez T, Gompels M, Jennings L, Ward L, Fox J, Lwanga J, Lee M, Gilson R, Leen C, Morris S, Clutterbuck D, Brady M, Asboe D, Fedele S, Fidler S, Brockmeyer N, Potthoff A, Skaletz-Rorowski A, Bogner J, Seybold U, Roider J, Jessen H, Jessen A, Ruzicic S, Stellbrink HJ, Kümmerle T, Lehmann C, Degen O, Bartel S, Hüfner A, Rockstroh J, Mohrmann K, Boesecke C, Krznaric I, Ingiliz P, Weber R, Grube C, Braun D, Günthard H, Wandeler G, Furrer H, Rauch A, Vernazza P, Schmid P, Rasi M, Borso D, Stratmann M, Caviezel O, Stoeckle M, Battegay M, Tarr P, Christinet V, Jouinot F, Isambert C, Bernasconi E, Bernasconi B, Gerstoft J, Jensen LP, Bayer AA, Ostergaard L, Yehdego Y, Bach A, Handberg P, Kronborg G, Pedersen SS, Bülow N, Ramskover B, Ristola M, Debnam O, Sutinen J, Blaxhult A, Ask R, Hildingsson-Lundh B, Westling K, Frisen EM, Cortney G, O'Dea S, De Wit S, Necsoi C, Vandekerckhove L, Goffard JC, Henrard S, Prins J, Nobel HH, Weijsenfeld A, Van Eeden A, Elsenburg L, Brinkman K, Vos D, Hoijenga I, Gisolf E, Van Bentum P, Verhagen D, Raffi F, Billaud E, Ohayon M, Gosset D, Fior A, Pialoux G, Thibaut P, Chas J, Leclercq V, Pechenot V, Coquelin V, Pradier C, Breaud S, Touzeau-Romer V, Rieger A, Kitchen-Maria Geit M, Sarcletti M, Gisinger M, Oellinger A, Antinori A, Menichetti S, Bini T, Mussini C, Meschiari M, Di Biagio A, Taramasso L, Celesia BM, Gussio M, Janeiro N.

Author information

Institute for Global Health, University College London, London, UK. Electronic address:
Institute for Global Health, University College London, London, UK.
Department of Infectious Diseases (CHIP), Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.
Division of Infectious Diseases and Hospital Epidemiology, Cantonal Hospital, St Gallen, Switzerland.
HIV i-Base, London, UK.
University Medical Centre Hamburg-Eppendorf, Hamburg, Germany.
European AIDS Treatment Group, Brussels, Belgium.
Hospital Clinico San Carlos and Universidad Complutense, Madrid, Spain.
Institute of Infection and Global Health, University of Liverpool, Liverpool, UK.
Institute of Infection and Global Health, University of Liverpool, Liverpool, UK; Department of Biomedical Sciences, University of West Attica, Athens, Greece.
AIDS Research Institute-IrsiCaixa, Hospital Universitari Germans Trias i Pujol and BCN Checkpoint, Badalona and Barcelona, Spain.
Istituto Nazionale per le Malattie Infettive Lazzaro Spallanzani IRCCS, Rome, Italy.
Chelsea and Westminster NHS Foundation Trust, London, UK.
Medical University of Vienna, Vienna, Austria.
Amsterdam UMC, University of Amsterdam, Amsterdam, Netherlands.
Venhälsan, Södersjukhuset, Stockholm, Sweden.
Department of Infectious Diseases and Hospital Epidemiology, University Hospital Zurich, University of Zurich, Zurich, Switzerland.
DC Klinieken, Amsterdam, Netherlands.
Centre for Sexual Health and Medicine, Walk in Ruhr, Ruhr University Bochum, Bochum, Germany.
Brighton and Sussex University Hospitals NHS Trust, and Brighton and Sussex Medical School, Brighton, UK.
Centro Sanitario Sandoval, Madrid, Spain.
Infectious Diseases Department, University Hospital (Centre Hospitalier Universitaire de Nantes) Hotel-Dieu, and INSERM UIC 1413 Nantes University, Nantes, France.
Medizinische Klinik und Poliklinik IV, University Hospital Munich, Munich, Germany.
Department of Infectious Diseases, Bern University Hospital, University of Bern, Bern, Switzerland.
Rigshospitalet, Copenhagen, Denmark.
Hospital General de Elche and Universidad Miguel Hernández, Alicante, Spain.
Onze Lieve Vrouwe Gasthuis (OLVG), Amsterdam, Netherlands.
Medical University Innsbruck, Innsbruck, Austria.
Aarhus University Hospital, Skejby, Denmark.
Hospital Clinic - IDIBAPS, University of Barcelona, Barcelona, Spain.
Helsinki University Hospital and University of Helsinki, Helsinki, Finland.
Praxis Jessen(2) + Kollegen, Berlin, Germany.
ICH Study Centre, Hamburg, Germany.



The level of evidence for HIV transmission risk through condomless sex in serodifferent gay couples with the HIV-positive partner taking virally suppressive antiretroviral therapy (ART) is limited compared with the evidence available for transmission risk in heterosexual couples. The aim of the second phase of the PARTNER study (PARTNER2) was to provide precise estimates of transmission risk in gay serodifferent partnerships.


The PARTNER study was a prospective observational study done at 75 sites in 14 European countries. The first phase of the study (PARTNER1; Sept 15, 2010, to May 31, 2014) recruited and followed up both heterosexual and gay serodifferent couples (HIV-positive partner taking suppressive ART) who reported condomless sex, whereas the PARTNER2 extension (to April 30, 2018) recruited and followed up gay couples only. At study visits, data collection included sexual behaviour questionnaires, HIV testing (HIV-negative partner), and HIV-1 viral load testing (HIV-positive partner). If a seroconversion occurred in the HIV-negative partner, anonymised phylogenetic analysis was done to compare HIV-1 pol and env sequences in both partners to identify linked transmissions. Couple-years of follow-up were eligible for inclusion if condomless sex was reported, use of pre-exposure prophylaxis or post-exposure prophylaxis was not reported by the HIV-negative partner, and the HIV-positive partner was virally suppressed (plasma HIV-1 RNA <200 copies per mL) at the most recent visit (within the past year). Incidence rate of HIV transmission was calculated as the number of phylogenetically linked HIV infections that occurred during eligible couple-years of follow-up divided by eligible couple-years of follow-up. Two-sided 95% CIs for the incidence rate of transmission were calculated using exact Poisson methods.


Between Sept 15, 2010, and July 31, 2017, 972 gay couples were enrolled, of which 782 provided 1593 eligible couple-years of follow-up with a median follow-up of 2·0 years (IQR 1·1-3·5). At baseline, median age for HIV-positive partners was 40 years (IQR 33-46) and couples reported condomless sex for a median of 1·0 years (IQR 0·4-2·9). During eligible couple-years of follow-up, couples reported condomless anal sex a total of 76 088 times. 288 (37%) of 777 HIV-negative men reported condomless sex with other partners. 15 new HIV infections occurred during eligible couple-years of follow-up, but none were phylogenetically linked within-couple transmissions, resulting in an HIV transmission rate of zero (upper 95% CI 0·23 per 100 couple-years of follow-up).


Our results provide a similar level of evidence on viral suppression and HIV transmission risk for gay men to that previously generated for heterosexual couples and suggest that the risk of HIV transmission in gay couples through condomless sex when HIV viral load is suppressed is effectively zero. Our findings support the message of the U=U (undetectable equals untransmittable) campaign, and the benefits of early testing and treatment for HIV.


National Institute for Health Research.

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