by Jeffrey T. Kirchner, DO, AAHIVS, AAHIVM Chief Medical Officer

May 23, 2019

Featured Literature:

Rodger AJ et al. for the PARTNER Study Group 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 multicenter, prospective, observational study. Lancet. Published Online May 2, 2019 S0140-6736(19)30418-0

There is strong evidence from HPTN 052 and the PARTNER studies confirming a negligible risk of HIV transmission through condomless sex in serodifferent heterosexual couples with the HIV-infected partner having an undetectable viral load while on ART. The PARTNER 1 study included patients from 14 countries who were followed at 75 clinical sites from 2010 to 2014. This recent publication from The Lancet includes data from the PARTNER 2 study which recruited and followed only gay couples. The patients were followed through April 2018. Couple-years of follow-up were eligible for inclusion if condomless sex was reported, use of PrEP or PEP was not reported by the HIV-negative partner, and the HIV-positive partner had a viral load of <200 copies per mL at the most recent visit. Data collected at quarterly visits included a sexual behavior questionnaire, HIV testing of the negative partner and viral load testing of the HIV-positive partner. If an HIV seroconversion occurred, anonymous phylogenetic analysis was done to compare HIV-1 pol and env sequences in both partners to determine if this was a linked transmission.

From September 2010 through July 2017, 972 couples were enrolled which provided 1593 couple-years of follow-up with a median of 2 years per couple. During eligible years of follow-up, couples reported condomless anal sex a total of 76,088 times. In addition, more than 30% of the HIV-negative men reported condomless sex with outside partners. Within this cohort, there were 15 new HIV infections diagnosed during eligible couple-years of follow-up. NONE of the new infections were phylogenetically linked within-couple transmissions, resulting in an HIV transmission rate of zero. The results of this study provide essentially the same level of evidence on viral suppression and lack of HIV transmission risk for gay men seen for heterosexual couples and suggest that the risk of HIV transmission in this population with condomless sex is effectively zero when HIV viral load is suppressed.

These data from the PARTNERS studies in addition to evidence for other studies fully support the message of U=U (undetectable equals untransmittable). These results also support and indirectly endorse the benefits of early HIV testing and treatment with ART. U=U is now endorsed by AAHIVM, the CDC and many other groups throughout the world. The web site is an excellent provider and patient resource for additional information on U=U.

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