July 15, 2016
This week, results from the PARTNER study show the strongest evidence yet that having an undetectable viral load prevents HIV transmission. Another study finds that an integrase inhibitor-based initial treatment regimen may be more efficacious than protease inhibitor-based regimens among women. To beat HIV, you have to follow the science!
Having an undetectable viral load led to zero linked HIV transmissions in the PARTNER study, which followed 1,166 serodiscordant couples with a positive partner on treatment and virally suppressed, and included about 58,000 instances of condomless sex.
The study provides the best evidence yet that having an undetectable viral load prevents HIV transmission. Additionally, the PARTNER study included both gay and heterosexual couples.
The study took place between September 2010 and May 2014 across 75 sites in 14 European countries.
The paper was published online in JAMA.
Among women, an integrase inhibitor-based initial HIV treatment regimen is more efficacious than protease inhibitor-based treatment, a study funded by Gilead Sciences found. Treatment-naive study participants were randomized to either the integrase arm (elvitegravir, cobicistat, emtricitabine and tenofovir disoproxil fumarate) or the protease arm (atazanavir, ritonavir, emtricitabine, and tenofovir disoproxil fumarate).
More women in the protease arm discontinued the drug due to side effects, especially rash, than did in the integrase arm, which drove the higher efficacy rates of the integrase arm. Similar trials involving men had previously shown the two regimens to be equally efficacious, but the discontinuation rates due to side effects had been lower among men.
Participants in the women-only study came from a variety of countries and revealed regional differences in virologic response across both regimens. The highest virologic response rates were among Ugandan women and the lowest among U.S. women. That outcome was related to lower adherence rates and greater loss to follow-up in the U.S. compared to the other study sites, study authors explained.
The study was published online in The Lancet.
A meta-analysis of 18 studies of pre-exposure prophylaxis (PrEP) using tenofovir disoproxil fumarate (TDF, Viread) in various populations found that the greatest reduction in the risk of acquiring HIV was seen in those who took PrEP more than 70% of the time compared to those who took a placebo.
There was some risk of developing resistance to emtricitabine (FTC, Emtriva) if PrEP using a combination of TDF and emtricitabine was started during acute HIV infection. People on PrEP did not engage in higher-risk sex than they had before starting this prevention method. However, clinical studies do not necessarily reflect behavioral changes in real-world settings, the authors cautioned.
Reports from San Francisco have shown lower condom use and higher rates of STIs when PrEP was implemented there. Women on PrEP did not experience higher rates of pregnancy problems or have their birth control pills work less effectively, this analysis showed, although it noted that two studies had reported higher pregnancy rates among PrEP users on oral contraceptives.
The study was published online in AIDS.
Warren Tong is the senior science editor for TheBody.com and TheBodyPRO.com. Follow Warren on Twitter: @WarrenAtTheBody.
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