About Treatment as Prevention

This fact sheet provides basic information on treatment as prevention, one of the options being tested now as part of the effort to identify additional tools to reduce the risk of HIV transmission and infection.

You can also download this information as a treatment as prevention fact sheet (PDF).

What is meant by ARV treatment as prevention?
"Treatment as prevention" is a term describing the use of antiretroviral drugs that are used to reduce the risk of passing HIV to others. The strategy would function as a secondary benefit of antiretroviral treatment after its primary purpose of improving an individual’s health. The rationale for this approach is that ARVs reduce viral load. Higher viral loads have been linked to increased risk of passing HIV to sexual partners. Treatment as prevention is an emerging area and there are different terms and phrases used to describe this approach, including "test and treat" and "testing and linkage to care plus," which recognizes that voluntary HIV testing and diagnosis is the first step to accessing care.

Why are we looking at treatment as prevention or "test and treat" strategies?
Right now, the decision about whether an individual with HIV starts ARVs is based on several factors, including the treatment guidelines in use wherever he or she lives. These guidelines may use factors like the individual's clinical health, infection with other diseases and opportunistic infections, T-cell count, and viral load tests (where available) to make a decision about whether to start ARVs. ARVs are not usually initiated with the goal of reducing the HIV-positive person's risk of passing the virus to others. The one exception is in the case of pregnant or breastfeeding mothers. Some strategies to reduce the risk of infection in infants call for treating the mother with ARVs, regardless of clinical guidelines, to reduce the risk of passing on HIV to the infant.

The treatment as prevention approach proposes, in some cases, starting people with HIV on ARVs when they are diagnosed, with the goal of reducing the chances that they will pass HIV onto others. The idea behind this strategy is that ARV treatment reduces viral load, and that lowering viral load (below a certain point) may greatly reduce the risk that a person with HIV will transmit the virus. This is supported by observational studies that show a relationship between low viral loads and reduced risk of transmitting HIV to sexual partners. Much of this information comes from studies in heterosexual populations. The relationship between lower viral load and reduced risk of transmission has also been observed in some studies of HIV-positive women breastfeeding their HIV-negative children. There is no strong evidence on lower viral load and reduction in transmission to needle-sharing partners. 

Such a strategy could have an impact on rates of new infections in some settings. However, there are many challenges, including current gaps in coverage of ARVs for people who are clinically eligible for them, low rates of HIV testing, additional scientific questions about the exact relationship between HIV viral load in the blood and risk of transmission, and the lack of consensus around the best time for individuals to begin treatment. The currently enrolling START (Strategic Timing of Antiretroviral Treatment) study is meant to provide guidance on when to start therapy. Until the results become available in around three to four years, it will remain unclear that starting treatment early would definitively benefit health outcomes. Without this information, advocacy for people to start treatment early for prevention purposes will continue to be debated. 

These uncertainties require additional research as well as policy and community discussions. This discussion and any future programmatic decisions require additional data and will inevitably need to balance individual benefits of treatment with possible wider-spread public health benefits of prevention.

How will we know if treatment as prevention works?
Unlike AIDS vaccine, microbicide or PrEP research, where there is a relatively clear pathway of clinical trials leading to a conclusion about a strategy, the use of ARVs to reduce infectiousness in HIV-positive people is unlikely to be proven through clinical research studies alone. Instead, treatment as prevention and test and treat strategies may be evaluated in specific trials and may also be implemented as part of common sense approaches to HIV risk-reduction based on what we already know.

There is one ongoing efficacy trial, called HPTN 052, which has enrolled 1,750 serodiscordant couples (one HIV-positive and one HIV-negative partner) to look at ARV treatment as prevention in a number of countries. It asks whether initiating treatment in the HIV-positive partner can help reduce the risk of sexual transmission of HIV to the HIV-negative partner. It is also looking at the possible benefits of early treatment versus those who delay initiating therapy until it is clinically indicated. All participants in the trial receive a basic prevention package including treatment for sexually transmitted infections, condoms and behavior change counseling.

There is also a planned feasibility study, HPTN 065, which is looking at a community-level test, link-to-care and, for those who need it based on current guidelines, treatment approach for HIV prevention in the US. The three-year study will take place in the Bronx, NY and Washington, DC. The study will look at whether this kind of approach is feasible for wide-scale implementation and public health impact -- researchers hope this kind of programming will lead to a decrease in HIV transmissions (through expanded testing, prevention for positives, linkage to care, initiation of treatment and increased treatment adherence).

Where is treatment as prevention research taking place?
The ongoing HPTN 052 study has trial sites in Brazil, India, Malawi, Thailand, United States, and Zimbabwe. HPTN 065 is scheduled to take place in two US cities: the Bronx, NY, and Washington, DC.

Who is involved in treatment as prevention and test and treat initiatives?
Use of ARV treatment for prevention will require input from service providers, activists, advocates, people living with HIV, policy makers, funders, and a range of other stakeholder groups. Many of these same groups are also paying close attention to the related issues raised by research on PrEP and other forms of ARV-based prevention in HIV-negative people.

When will we get research results?
There may never be a conclusive set of trial data that clarify the HIV risk-reduction benefits of early ARV treatment for all populations. However, it will be critical to monitor, collate, and analyze data from the full range of research projects and the single current randomized trial (due to release results in 2013) to develop a sense of how this strategy might be used. It will be equally important to assess the risks and benefits of a test and treat or treatment as prevention approach for HIV-positive people. Will rates of coercive or non-voluntary testing go up? Will there be adverse toxicities or additional resistance issues raised by earlier initiation of treatment? Will individuals continue to have the choice about whether to start ARVs? AVAC will continue to explore these and other issues as the research progresses.
 

Visit the HIV prevention research timeline and trials map for details on other ongoing biomedical HIV prevention research trials. 

Click here for a table of ongoing treatment as prevention trials.