May 13, 2011
This week the National Institutes of Health (NIH) released findings from a large-scale clinical study which concluded that men and women with HIV reduced their risk of transmitting the virus to their heterosexual partners by 96% when taking oral antiretroviral therapy (ART). The study also found that treatment earlier in the course of HIV reduced the incidence of HIV-associated diseases, especially tuberculosis. These results represent the strongest evidence to date that early HIV treatment dramatically reduces the chance that an HIV positive individual will transmit the virus to a sexual partner.
The clinical trial, known as HPTN 052, began in April 2005 and enrolled 1,763 couples, 97 % of whom were heterosexual. The study was conducted at 13 sites in Botswana, Brazil, India, Malawi, South Africa, Thailand, the United States, Zimbabwe and CDC’s research center in Kenya. At the time of enrollment, the HIV-infected partners (890 men, 873 women) had CD4+ T-cell levels—a key measure of immune system health—between 350 and 550 cells per cubic millimeter (mm³). Throughout the study, both groups received HIV-related care that included counseling on safe sex practices, free condoms, treatment for sexually transmitted infections, regular HIV testing, and frequent evaluation and treatment for any complications related to HIV infection. Each group received the same amount of care and counseling.
The trial was scheduled to end in 2015 but was stopped early after an interim review of the study data by an independent data and safety monitoring board (DSMB) concluded that use of ART by HIV-infected individuals reduced the chance that they would transmit to their partners and was associated with reduced incidence of tuberculosis in the partner with HIV. The results in this trial indicate both clinical and prevention benefits for ART and these accrue, even for people with
relatively high CD4 cell counts. The results support the Department of Health and Human Services guidelines for the use of ART (http://www.aidsinfo.nih.gov/contentfiles/AdultandAdolescentGL.pdf) that recommend ART for people with CD4 counts less than 500 cells/ml and are permissive for treatment above this level for potential clinical and prevention benefits.
While today's announcement provides cause for optimism that this approach may help reduce new HIV infections overall in the United States and around the world, the degree of impact at a population level will depend on many factors, including the real-world feasibility of scaling up intensive testing and care services in a broad range of settings, as well as the ability for individuals to maintain high levels of drug adherence over time. CDC is working with NIH and local health departments to assess the feasibility of expanded testing, improving HIV treatment, and linking to care in the United States in HPTN 065, which examines the feasibility of events necessary for “test and treat” programs to succeed. Key components of this study include expanded testing, linkage to care, the initiation of ART, adherence to ART with viral suppression, and prevention with positives. The study will also look at the use of financial incentives to improve linkage and adherence. CDC’s surveillance system will be used to measure the study outcomes.
The results of HPTN 052 confirm the importance of the nation’s increasing focus on expanded testing, treatment and prevention strategies for HIV-infected persons, but diagnosis and treatment alone will likely not end the HIV epidemic in the United States. In addition, the majority of the U.S. epidemic occurs among men who have sex with men (MSM) and the transmission dynamics may differ in this population, so the prevention benefits identified in this study may not be directly extrapolated to this population. Despite all of these challenges, the HPTN 052 findings add to an existing strong mix of effective prevention interventions that can make a significant difference in this country’s HIV epidemic. CDC is working to identify the combination of high-impact prevention strategies that are likely to yield the greatest impact on the U.S. epidemic. For example, we are currently conducting demonstration projects in 12 of the hardest hit cities in the United States with the goal of identifying the most effective combination of prevention interventions in each area to reduce infections. CDC is also working to improve surveillance systems to better capture CD4 and viral load levels that will help monitor the national epidemic. Furthermore, at a national level, we are pursuing a tiered, combination approach to HIV prevention that will prioritize intensive interventions for HIV positive individuals and very high risk individuals; community level and structural interventions in highly impacted areas; and fundamental knowledge among all Americans to create an enabling and supportive environment necessary for success.
The HPTN 052 trial results represent a significant advance in HIV prevention research, but because no prevention strategy is one hundred percent effective, including ART, it is important that individuals at risk for acquiring or transmitting HIV continue to use condoms and other proven risk reduction strategies. Individuals infected with HIV should not simply assume that they are not infectious to their partners, if they are on treatment.
This is an exciting development in HIV prevention, and we look forward to working together to implement these findings in practice as part of high-impact prevention and care strategies.
/Kevin A. Fenton/
Kevin A. Fenton
Director, National Center for HIV/AIDS Hepatitis, STD, and TB Prevention
/Jonathan H. Mermin/
Jonathan H. Mermin
Director, Division of HIV/AIDS Prevention National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention