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No HIV Transmissions in Gay Couples if HIV+ Partner Has Undetectable Virus
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9th IAS Conference on HIV Science (IAS 2017), July 23-26, 2017, Paris
Mark Mascolini
A three-country observational study, Opposites Attract, found no genetically linked HIV transmissions in gay couples when the HIV-positive partner had an undetectable viral load [1]. The 343-couple study recorded more than 12,000 condom-free anal sex acts in which the HIV-negative partner was protected only by his positive partner's undetectable load--not by PrEP. The results confirm findings in the European PARTNER Study of gay couples [2].
Opposites Attract recruited HIV-discordant couples (one partner HIV-negative/one partner HIV-positive) from three Australian cities, from Rio De Janeiro, Brazil, and from Bangkok, Thailand. The positive partner did not have to be taking antiretroviral therapy (ART), and the negative partner could use PrEP. Couples had to have regular anal sex, and there were no condom requirements. Couples made study visits twice a year. During the visit, researchers measured the positive partner's viral load and tested the negative partner for HIV infection.
The researchers signed up 358 couples, 343 of which had at least one follow-up visit. Follow-up ended on December 31, 2016. Australia provided 157 couples, Bangkok 105, and Rio 96. Follow-up averaged about 1.5 years per couple.
About three quarters of HIV-positive partners took ART throughout follow-up, and most of the rest started therapy during the study period. Three quarters of the positive group had an undetectable viral load throughout follow-up, and about three quarters of couples had anal sex without condoms during the study. About one third of HIV-negative partners used PrEP at some point during the study.
No HIV-negative man became infected with the HIV of his positive partner. During the study there were more than 12,000 bouts of condom-free anal sex in which the positive partner had an undetectable viral load (below 200 copies) and the negative partner was not taking PrEP. The researchers estimated that the risk of HIV transmission during condom-free anal sex ranged from 0 to 1.56% per year, somewhat lower than the estimate in the PARTNER Study (0 to 2.70% per year).
Combining Opposites Attract and PARTNER data, the researchers counted 34,911 acts of condom-free anal sex during which the positive partner had an undetectable viral load and the negative partner did not use PrEP. The Opposites Attract team believes their primary finding "provides further evidence to add to previous studies that HIV transmission when someone's viral load is undetectable is extremely unlikely, if not impossible." They proposed that "condomless sex with [an] undetectable viral load is a form of safe sex." But they cautioned that viral load remains detectable in the first months after a person starts ART, so HIV transmission may be possible in that period.
References
1. Bavinton B, Grinsztejn B, Phanuphak N, et al. HIV treatment prevents HIV transmission in male serodiscordant couples in Australia, Thailand and Brazil. 9th IAS Conference on HIV Science (IAS 2017), July 23-26, 2017, Paris. Abstract TUAC0506LB.
2. Rodger A. Association between sexual activity without condoms and risk of HIV transmission in serodifferent couples when the HIV-positive partner is using suppressive antiretroviral therapy: the PARTNER study. 21st International AIDS Conference (AIDS 2016). July 18-22, 2016. Durban, South Africa. Abstract TUAC0206.http://www.natap.org/2016/IAC/IAC_08.htm
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Oral study presentation at IAS 2017. They followed 358 gay make serodiscordant couples from Australia, Rio de Janiero & Thailand. Read their full press release explaining the results below, where they say ".....the most important point is that we found an HIV transmission rate of zero within the Opposites Attract Study couples......This is an exciting result and provides further evidence to add to previous studies that HIV transmission when someone's viral load is undetectable is extremely unlikely, if not impossible......We found that for anal sex without a condom when the HIV-positive partner had undetectable viral load (defined as less than 200 copies per mL), the "true" risk of transmission could be between zero and 1.56% per year, with a very small chance that the per-year risk could be higher. The couples in Opposites Attract reported over 12 thousand acts of condomless anal sex when the HIV-positive partner had undetectable viral load and the HIV-negative partner was not on PrEP."
- Conclusions: There were no linked HIV transmissions in almost 600 CYFU involving close to 17,000 acts of CLAI in HM-SDC. Our results provide strong support for the hypothesis that undetectable viral load prevents HIV transmission in homosexual men.
Andrew Grulich
B. Bavinton1, B. Grinsztejn2, N. Phanuphak3, F. Jin1, I. Zablotska1, G. Prestage1, A. Kelleher1, A. Pinto1, D. Cooper1, A. Grulich1, The Opposites Attract Study Group
Institutions
1University of New South Wales, Kirby Institute, Sydney, Australia, 2Instituto de Pesquisa Clínica Evandro Chagas, Rio de Janeiro, Brazil, 3Thai Red Cross, AIDS Research Centre, Bangkok, Thailand
Background: Prospective data on the association of HIV transmission and undetectable viral load (UVL) in homosexual male HIV-serodiscordant couples (HM-SDC) are extremely limited. We report the final results from the Opposites Attract cohort study of HM-SDC in Australia, Bangkok and Rio de Janeiro.
Methods: HM-SDC were recruited through clinics. Information on sexual behaviours was collected at each visit from the HIV-negative partner (HNP). HNPs were tested at baseline and follow-up for HIV antibodies/sexually transmitted infections (STIs), and positive partners (HPPs) for HIV viral load/STIs. Phylogenetic analysis of pol and env genes was performed to identify linked HIV transmissions within couples based on genetic distance and monophyletic grouping. Incidence was calculated per couple-year of follow-up (CYFU), and stratified by pre-exposure prophylaxis (PrEP) use and by whether different forms of condomless anal intercourse (CLAI) were reported. UVL was defined as < 200 copies/mL. One-sided upper 95% confidence limits (UCL) were calculated.
Results: By end 2016, 358 HM-SDC were enrolled: 157, 105 and 96 from Australia, Thailand and Brazil respectively. There were 591 CYFU in 343 couples with at least one follow-up visit of whom 57.4% reported anal sex with outside partners during any point in follow-up. At baseline, 79.9% of HPPs were on anti-retroviral therapy (ART) and 77.9% had UVL; STI prevalence was 14.3%/11.7% in HPPs/HNPs respectively. There were 318 CYFU in periods where CLAI was reported with a total of 16,889 acts of CLAI. There were 3 new HIV infections but no linked transmissions. The overall UCL of the transmission rate when CLAI was reported was 1.16/100 CYFU, and it was 1.56/100 CYFU when there was UVL.
Conclusions: There were no linked HIV transmissions in almost 600 CYFU involving close to 17,000 acts of CLAI in HM-SDC. Our results provide strong support for the hypothesis that undetectable viral load prevents HIV transmission in homosexual men.
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there are 2 press releases from the study authors: #1 -
https://kirby.unsw.edu.au/news/effective-hiv-treatment-halts-hiv-transmission-among-homosexual-couples-study-finds
Effective HIV treatment halts HIV transmission among homosexual couples, study finds
"This is life-changing news for couples of differing HIV status. But it is important that the HIV positive partner is under regular medical care and does not miss any of their anti-retroviral medication in order to ensure they maintain an undetectable viral load" said Professor Grulich. "Our data add to previous studies which show that there has never been a recorded case of HIV transmission from an HIV-positive person to their HIV-negative sexual partner when the HIV-positive partner had undetectable viral load."....."Undetectable virus level effectively prevents HIV transmission among gay couples," said Professor Andrew Grulich from the Kirby Institute and chief investigator on the study. "Opposites Attract is the first study to show that these results apply in both high and middle income countries. Our research adds to the evidence from a small number of other international studies of heterosexual and homosexual couples and means that we can say, with confidence, that effectively treated HIV blocks transmission in couples of differing HIV status."
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2nd press release from study authors:
The study recruited a total of 358 gay male serodiscordant couples: 157 of these couples were from Australia, 96 were from Rio de Janeiro, and 105 were from Bangkok. Of the total 358 couples enrolled, the final analysis focused only on the 343 couples who had attended at least one follow-up visit by the end of the study. These couples were in the study for an average time of just over one-and-a-half years. A total of 591 couple-years of follow-up were included in the analysis. "Couple-years of follow-up" means the cumulative total amount of time that all the couples were in the study.
There were no "linked" HIV transmissions in these couples. A "linked" transmission is where genetic analysis of the virus shows that the HIV came from the HIV-positive partner in the couple to his HIV-negative partner. So, no HIV-negative man in the study contracted HIV from his HIV-positive study partner.
Because we found no "linked" transmissions, the focus of the analysis becomes about how confident we are that the zero rate of transmission we observed in the study is actually "true". Even though the transmission rate in Opposites Attract was zero, there is a statistical chance that the "true" transmission rate could be higher.
We found that for anal sex without a condom when the HIV-positive partner had undetectable viral load (defined as less than 200 copies per mL), the "true" risk of transmission could be between zero and 1.56% per year, with a very small chance that the per-year risk could be higher. The couples in Opposites Attract reported over 12 thousand acts of condomless anal sex when the HIV-positive partner had undetectable viral load and the HIV-negative partner was not on PrEP.
This is an exciting result and provides further evidence to add to previous studies that HIV transmission when someone's viral load is undetectable is extremely unlikely, if not impossible.
There were 3 new infections in initially HIV-negative partners during follow-up, all from outside sexual partners, which equated to an incidence rate of 0.5% per year. This is quite a low incidence rate. Even though the incidence rate was fairly low, this means that HIV-negative partners who are having condomless sex with outside partners should consider going on PrEP.
However, the most important point is that we found an HIV transmission rate of zero within the Opposites Attract Study couples.
In homosexual and heterosexual couples, there has never been a recorded case of HIV transmission from an HIV-positive person to their HIV-negative sexual partner when the HIV-positive partner had undetectable viral load.
Between Opposites Attract and the PARTNER Study, there have now been a combined 34,911 acts of condomless anal sex reported in gay couples when the HIV-positive partner had undetectable viral load and the HIV-negative partner was not taking PrEP. We can now be confident that condomless sex with undetectable viral load is a form of safe sex.
However, it is important to remember that when the HIV-positive partner is in the first six months of starting HIV treatment, it can take a little bit of time for the viral load to become undetectable. There have been some cases overseas in heterosexuals where transmission happened when the HIV-positive partner was on treatment but was not yet undetectable. So, during the first six months of treatment and until the viral load is undetectable, it is best to use condoms or for the HIV-negative partner to take PrEP. It is also important to monitor and treat sexually transmitted infections.
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