Sexual transmission risk low if HIV-positive partner is on ART, virally suppressed
BOSTON — There appears to be low risk for HIV transmission through unprotected anal or vaginal sex between serodiscordant couples if the HIV-positive partner is on antiretroviral therapy and has achieved viral suppression, according to interim results from the PARTNER study, presented here.
However, there remains some uncertainty about the absolute risk for transmission, particularly pertaining to anal sex.
The study was conducted partly in response to a statement made by the Swiss National AIDS Commission in 2008 — known as the “Swiss statement” — which suggested that a patient with HIV who is on ART and has completely suppressed viral load is not sexually infectious, according to Jens Lundgren, MD, chief physician and director of the Copenhagen HIV Program in Denmark, who presented the findings at a press conference during the 2014 Conference on Retroviruses and Opportunistic Infections.
The observational, multicenter PARTNER study followed 767 serodiscordant couples who had condomless anal or vaginal sex 1 month before enrollment. Every 6 months, the HIV-positive partners, who received ART, completed a questionnaire assessing sexual behavior, whereas the HIV-negative partners were screened for infection. Genetic analyses allowed the researchers to link infections between couples.
According to the researchers, the study has documented nearly 900 couple-years of follow-up, during which time there were 44,500 sexual acts without condoms. If ART had failed, this number of sexual acts would result in 50 to 120 new transmissions, based on past projections.
Although some partners acquired HIV during the study period, there was no evidence of linked transmission between couples — a zero rate of HIV transmission (95% CI, 0-0.4/100 couple-years of follow-up). Based on the upper limit of the confidence interval, one in 25 would have become infected over 10 years without the use of condoms.
“The uncertainty is particularly advanced for anal sex, where we do not have sufficient data to exclude that one in 10 would be infected over a 10-year period,” Lundgren said.
Lundgren added that the PARTNER study will continue through 2017, and additional data will be released. – by John Schoen
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Disclosure: The researchers report no relevant financial disclosures.