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 page as a treatment as
prevention fact sheet (PDF) in English, French, Portuguese, Spanish and Thai.
English PDF and text below last updated January 2012. The other PDFs were last updated June 2010.
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
(ART) 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
different strategies using this approach. These
include “test and treat” and “testing and
linkage to care plus (TLC-plus)”. You may
also see a range of acronyms that represent
this concept—e.g., TasP, TNT, TLC+ and
T4P.
Why is treatment as prevention being
evaluated as an HIV prevention
strategy?
There are data from observational studies,
which have shown that HIV-positive people with
low or undetectable viral load levels have
reduced risk of transmitting to their partners
compared to HIV-positive people with higher
viral loads. These observational data provided
a rationale for conducting a randomized
controlled trial of combination ART as a tool
to reduce the risk of transmission between
sexual partners. Prevention of vertical
transmission programs also recognize the
effectiveness of providing combination ART to
the pregnant woman, regardless of her CD4 cell
count, as a strategy for reducing risk of
passing HIV to an infant at birth.
It is important to note that right now, the decision about whether an individual with HIV begins ART 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/or viral load tests (where available) to help an individual make the decision whether to start ART. Except in prevention of vertical transmission programs, ART is not initiated with the primary goal of reducing the HIV-positive person’s risk of passing the virus to others.
There is no strong evidence on viral load and reduction in transmission to needle-sharing partners—the data on the effect of treatment as prevention is limited to individuals whose primary risk of HIV is via sexual exposure.
What are the data on treatment as
prevention?
There is one ongoing efficacy trial, called
HPTN 052, which enrolled 1,763 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
and whether the effect is a durable one. 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.
How realistic is the treatment as
prevention approach as an HIV prevention
tool?
HPTN 052 showed a powerful benefit, however
there are many challenges in deploying
treatment as a prevention strategy, including
current gaps in coverage of ARVs for people who
are clinically eligible for them, low rates of
HIV testing, challenges to keeping people in
care, 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. These
challenges require additional research as well
as policy and community discussions. These
discussions and 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.
What additional data relevant to
treatment as prevention can be
expected?
The currently enrolling START (Strategic Timing
of AntiRetroviral Treatment), which is a
randomized study of early versus deferred
treatment, is meant to provide guidance on when
to start therapy. The results from START are
expected in four to five years—the trial is
meant to provide definitive data on the effect
of early treatment on health outcomes in
HIV-positive people (including effect of early
treatment on non-AIDS morbidity and
mortality).
In addition to the need to evaluate the effect of early treatment on individual-level health outcomes, it is important to consider the feasibility of such an approach and how to ensure future programming could have maximum impact. The HPTN 065 study is looking at feasibility of an expanded 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 is ongoing in the Bronx, NY, and Washington, DC. The study is designed to determine whether this kind of approach is feasible for wide-scale implementation and public health impact by examining different approaches to testing, prevention for positives, linkage to care, initiation of treatment and increased treatment adherence, all of which are essential to a successful treatment as prevention intervention.
There are a number of other studies gathering data relevant to treatment as prevention, the details of which can be found in the treatment as prevention trials table available at www.avac.org/treatmentasprevention.
Other important questions that the current trials relevant to treatment as prevention may not fully address include: Can voluntary HIV testing be expanded? 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. Colleagues at the AIDS Foundation of Chicago are leading a collaborative effort to develop and nurture a research-driven, community-led global understanding of the emerging evidence base around the adoption of antiretroviral-based prevention strategies—partners include AIDS United (Washington, DC), NAZ India (Delhi), Desmond Tutu HIV Foundation (Cape Town), RAND Europe, and Bairds CMC. More information is available at mappingpathways.blogspot.com.
Priorities for 2012
AVAC’s Playbook 2012 sets out top strategic
goals and priorities in HIV prevention for
ourselves—and for the world. Here’s what we
have to say about treatment as prevention. For
more, visit www.avac.org/playbook.
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.