Weber, Jonathan; Tatoud, Roger; Fidler, Sarah
AIDS 24 (S4): S27–S39, 2010.
This review considers the use of antiretroviral drugs specifically to prevent HIV transmission. Antiretroviral therapy (ART) can be implemented for the protection of uninfected individuals both before (preexposure prophylaxis) and after (postexposure prophylaxis) exposure to HIV infection. Preexposure prophylaxis may be used coitally dependently when individuals are intermittently exposed or by continuous daily dosing for those constantly exposed; postexposure prophylaxis is used in 28-day courses. Alternatively, ART can be used strategically to reduce the viral load and consequent infectiousness of an HIV-infected individual, thereby limiting the risk of onward viral transmission. A policy of universal HIV testing to enhance the identification of all HIV-positive individuals followed by immediate treatment of all HIV-positive individuals, irrespective of their CD4 cell counts (universal test and treat), has been postulated as a potential tool capable of reducing HIV incidence at a population level. This concept represents a paradigm shift in the use of ART, targeting infectious individuals for prevention rather than protecting uninfected exposed populations. This strategy could have the advantage of preventing transmission and reducing HIV incidence at a population level, as well as delivering universal access to therapy for all people living with HIV and AIDS, potentially eliminating mother-to-child HIV transmission and limiting concomitant diseases such as tuberculosis. This review critically examines the scientific basis of ART for HIV prevention, summarizing the risks and opportunities of the potential expansion of ART for prevention. Specifically, we consider the evidences for and against targeting HIV-uninfected individuals compared with enhanced HIV testing and treatment of HIV-infected individuals in terms of impact on viral transmission.?
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Attendees at the 18th International AIDS conference held in Vienna in July 2010 felt a tremor of hope when Prof. Salim Abdool Karim received a standing ovation following the announcement that a vaginal gel containing the anti-HIV drug tenofovir could reduce the risk of HIV infection by 39%. The groundbreaking results came out of the CAPRISA clinical trial conducted amongst 900 women in rural Vulindela district (KwaZulu-Natal) and urban Durban, South Africa. Euphoria followed in the audience, online and later in the printed media. After 30 years of limited success, the field of HIV prevention could potentially add a new powerful tool to circumcision, condoms, and the prevention of mother to child transmission. Most remarkably, that tool is in women’s hands and the story could unfold with even more good news if it weren’t for a small setback: funding the next clinical studies. Read the rest of this entry »
Being infected with HIV is not just a question of having unsafe sex with someone who is HIV+. Such reductionist approach ignores the complex set of factors, circumstances and events that lead to unsafe sex to take place. This concept map tries to survey these factors starting from the remote to the more intimate. As always, this is a work in progress and comments and suggestions are welcome.
Despite the interesting results of an HIV vaccine trial in Thailand (RV144), HIV prevention is still limited to a small number of options many of which are not bullet-proof. Biomedical interventions based on vaccines and microbicides are still a long shot away. Conversely, treatment is working well in bringing HIV-infected people back to a normal life and potentially reducing the risk of HIV transmission by reducing their viral load. The use of antiretroviral drugs as a means to prevent HIV infection is controversial and a lot of background work will be required before embarking on massive “Test and Treat” campaigns.
What is good enough? Who decides?
This presentation was prepared for an IRMA global teleconference on December 4, 2009.
Microbicides are compounds that can be applied inside the vagina or rectum to protect against sexually transmitted infections (STIs) including HIV. They can be formulated as gels, creams, films, or suppositories. Microbicides may or may not have spermicidal activity (contraceptive effect). At present, an effective microbicide is not available (WHO definition)
Pre-exposure prophylaxis (PrEP) is an experimental HIV-prevention strategy that proposes using antiretrovirals (ARVs) to reduce the risk of HIV infection in healthy uninfected people at risk of acquiring the virus. PrEP is not proven to work and is currently being tested in HIV-negative people in several clinical trials across the world. It is a controversial strategy that raises many hopes but also many questions (Updated May 1, 2010).
For further information check the PrEPWatch Website.
To use or not to use a condom for sexual intercourse is the result of a combination of several interacting factors. From the rational decision to choose not to use condoms to that of not being able to choose to use them, there is a broad range of possible accounts.
Addressing poor condom use therefore is not a question of simply promoting them but a question of knowing and understanding these numerous factors, their interactions and additive effects and ultimately understanding what leads people to do what they do or can do in their individual situation with their own perspectives, understanding, resources and options.
Several factors are important in determining if the HIV virus can be passed from an infected person to another one. These include biological and social factors which both relate to the exposed and the “infector” individuals.
This conceptual framework summarises only the biological factors that influence HIV transmission. When assessing the risk of infection, each should be considered in turn and as a whole.
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