FRIDAY, May 3, 2019 (HealthDay News) -- In HIV serodifferent gay couples, the within-couple rate of HIV transmission through condomless anal sex is zero when the HIV-positive partner is taking suppressive antiretroviral therapy (ART), according to a study published online May 2 in The Lancet.
Alison J. Rodger, M.D., from University College London, and colleagues conducted a prospective, observational study at 75 sites in 14 European countries. In the first phase, heterosexual and gay serodifferent couples who reported condomless sex were recruited and followed up. The HIV-positive partner was taking ART. In the second phase, only gay couples were recruited and followed up. A total of 979 gay couples were enrolled from Sept. 15, 2010, through July 31, 2017. Of those, 782 provided 1,593 eligible couple-years of follow-up.
The researchers found that couples reported condomless sex for a median of 1.0 year. During eligible couple-years of follow-up, condomless anal sex was reported 76,088 times. Condomless sex with other partners was reported by 37 percent of HIV-negative men. During eligible couple-years of follow-up, 15 new HIV infections occurred; none were phylogenetically linked within-couple transmissions, indicating an HIV transmission rate of zero.
"Our findings provide conclusive evidence that the risk of HIV transmission through anal sex when HIV viral load is suppressed is effectively zero," the authors write.
Several authors disclosed financial ties to pharmaceutical companies, including Gilead Sciences and ViiV Healthcare, which provided unrestricted grant funding.