By Rebecca Bowers

EXECUTIVE SUMMARY

New research indicates that antiretroviral treatment that leads to viral suppression prevents sexual transmission of HIV in discordant gay male couples as well as it does among heterosexual couples.

  • While earlier studies had provided evidence of the effect of antiretroviral therapy (ART) on the risk of HIV transmission between discordant heterosexual mixed-status couples (where one partner was HIV-positive and the other was HIV-negative), limited data have been available on ART’s effectiveness for preventing HIV transmission in discordant gay couples.
  • A total of 782 couples provided results over 1,593 couple-years of follow-up. The investigators reported no episodes of HIV transmission from the HIV-positive partners to their HIV-negative sexual partners.

New research indicates that antiretroviral treatment that leads to viral suppression prevents sexual transmission of HIV between discordant gay male couples as well as it does among heterosexual couples.1 While earlier studies had provided evidence of the effect of antiretroviral therapy (ART) on the risk of HIV transmission between heterosexual mixed-status couples (where one partner was HIV-positive and the other was HIV-negative), limited data have been available on ART’s effectiveness at preventing HIV transmission in discordant gay couples.2,3

The new results reported from the PARTNER2 trial mirror those observed in previous studies, which indicated that antiretroviral treatment that leads to viral suppression prevents sexual transmission of HIV between discordant gay male couples as well as it does among heterosexual couples. Investigators noted that the current study offers an important finding, since anal sex carries a higher risk of transmission than vaginal sex.

The current study “unequivocally” demonstrates the concept of Undetectable = Untransmittable (U=U), which is integral to the four strategies of the national campaign for ending the HIV epidemic in the United States, says Carl Dieffenbach, PhD, director of the Division of AIDS at the National Institute of Allergy and Infectious Diseases.

“These strategies include getting more people tested and, if they test positive, into HIV care and on treatment,” said Dieffenbach in a press statement. “When a person with HIV is in care and HIV treatment durably suppresses their viral load, three important things happen — he or she can live a long and healthy life, he or she won’t transmit the virus, and finally, the stigma that has long been associated with HIV diminishes.”

Review the Results

The PARTNER2 trial was launched following the 2016 report of the initial PARTNER study, in which researchers enrolled 1,166 serodifferent couples at 75 sites in 14 European countries between 2010 and 2014.3 The original study included 340 gay couples. Since the estimate for HIV transmission among gay couples was less precise than the estimate of transmission for heterosexual couples because of the lower number of
accrued couple-years of follow-up, the investigators launched the PARTNER2 study.

From 2014 to 2017, the researchers continued recruiting 495 additional gay couples to participate in the PARTNER2 study. In the PARTNER2 trial, the HIV-positive partner in each couple was on treatment and had regular laboratory tests to confirm a viral load of less than 200 copies/mL. Investigators checked that the HIV-negative partner was tested regularly for HIV. All couples engaged in sex without condoms and without the HIV-negative partner using HIV pre- or post-exposure prophylaxis.

A total of 782 couples provided evaluable results over 1,593 couple-years of follow-up. This included 76,088 self-reported episodes of anal intercourse without using condoms. The researchers reported no episodes of HIV transmission from the HIV-positive partners to their HIV-negative partners.1 Although 15 people became infected with HIV during the study, virus screening showed that none of the new infections were linked to the HIV-positive partners in the study, but came from a sexual partner outside of the couple. Investigators estimated that within the study, which took place across 14 European countries, around 472 HIV transmissions were averted over the eight years of the trial.1

Time to Act Is Now

Alison Rodger, MD, professor at the University College London’s Institute for Global Health and lead author of the study, says the current paper provides “conclusive evidence” for gay men that the risk of HIV transmission with suppressive ART is zero.

“Our findings support the message of the international U=U campaign, that a suppressed viral load makes HIV untransmittable,” said Rodger in a press statement. “This message has been endorsed by more than 780 HIV organizations in 96 countries and can help end the HIV pandemic by preventing HIV transmission, and tackling the stigma and discrimination that many people with HIV face.”

Public health officials now must strive to make sure that all HIV-positive people have access to testing, treatment, support for adherence, and linkage to care to help patients maintain an undetectable viral load, Rodger said.

“It is crucial to implement science with importance for the involved community and people living with HIV,” said Jens Lundgren, MD, professor of infectious diseases at Rigshospitalet, University of Copenhagen and co-investigator in the PARTNER study. “We have now provided the conclusive scientific evidence for how treatment effectively prevents further sexual transmission of HIV.”

REFERENCES

  1. Rodger AJ, Cambiano V, Bruun T, et al. 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. Lancet 2019. doi:10.1016/S0140-6736(19)30418-0. [Epub ahead of print].
  2. Cohen MS, Chen YQ, McCauley M, et al. Prevention of HIV-1 infection with early antiretroviral therapy. N Engl J Med 2011;365:493-450.
  3. Rodger AJ, Cambiano V, Bruun T, et al. Sexual activity without condoms and risk of HIV transmission in serodifferent couples when the
    HIV-positive partner is using suppressive antiretroviral therapy. JAMA 2016;316:171-181.