A pre-meeting session at the International AIDS Society conference in Rome was originally expected to feature the release of World Health Organization (WHO) guidance on HIV counseling and testing and access to antiretroviral therapy (ART) for “sero-discordant couples” – where one partner is HIV-infected and the other is not. Instead, the session highlighted a “work in progress” in the context of clinical trial results confirming the efficacy of HIV treatment and pre-exposure prophylaxis (PrEP) using antiretrovirals as HIV prevention.
Principal Investigator of HPTN 052 Dr. Myron Cohen reminded the audience of the findings of this landmark clinical trial, where ART in the HIV-infected partner was more than 96 percent effective in preventing HIV transmission in the uninfected partner and demonstrated health benefits to the infected partner. The trial also reported that 17 of the 27 HIV transmission events that occurred in the delayed treatment arm were transmissions from infected partners with CD4 counts greater than 350.
Lead on the first ever WHO guidance relevant to couples, Dr. Rachel Baggaley outlined the guidance development process, which began well before HPTN 052 results became available but have ultimately been informed by the compelling results of the study. Baggaley noted the substantial evidence that significant numbers of HIV infections in sub-Saharan Africa occur in the context of stable couple relationships. One study in Zambia found that 87 percent of genetically linked infections could be linked to cohabiting partners. She outlined some of the numerous benefits associated with couples counseling and testing including earlier access to ART for infected partners, opportunities for family planning and more consistent use of condoms, facilitating linkages to medical male circumcision for HIV-uninfected men, and strengthening relationships. Dr. Connie Cellum, principal investigator of the Partners PrEP study, also noted the need to end the separation of HIV testing from service delivery to effectively access couples and noted the potential high yield of home-based testing of partners given the challenges of getting couples to healthcare settings.
The WHO guidance dates includes the following five key recommendations:
- Couples or partners should be offered voluntary HIV counseling and testing to support mutual disclosure of HIV status.
- Couples or partners should be offered voluntary HIV counseling and testing to support mutual disclosure in antenatal settings.
- Partners who test positive for HIV infection in the context of couples counseling and testing should be offered ART for the benefit of their own health.
- Partners who test positive for HIV infection in the context of couples counseling and testing should be advised that if they take ART, it can also benefit their HIV uninfected sexual partner(s).
- Partners who test positive for HIV infection with CD4 counts greater than 350 should be offered ART to prevent transmission to their sexual partner(s).
WHO hopes to finalize the guidance in the near future after further consideration of several additional important issues. One issue is the two recent clinical trial results of the use of PREP in the context of discordant couples that showed a strong prevention benefit. Another is the relevance of couples counseling and testing to men who have sex with men (MSM) in couples and couples who inject drugs.
Dr. John Stover of the Futures Institute presented some preliminary modeling data relevant to the draft guidance. One element of the model includes estimates of the percentage of HIV infections that likely occur in the context of discordant couples. Notably, percentages are higher in countries where HIV prevalence is lower. For instance, in Ethiopia the estimate is that 40 percent of infections occur in discordant couples while in Kenya the estimate is 12 percent. Stover’s modeling looks at building on the WHO HIV investment framework by estimating the cost and impact of testing and treating 10 percent of discordant couples and 20 percent of discordant couples. The estimated cost per infection averted is $10-$15,000. This intervention would avert 400,000 to 760,000 new HIV infections and avert 350,000 to 650,000 AIDS deaths.
Dr. David Hoos from UNAIDS summed up the excitement associated with prevention trial results this year: “I believe that we will remember 2011 as a turning point in the AIDS epidemic in the same fashion we remember 1996 as the year we identified effective therapy for HIV infection.”