Letter to the Editor
To the Editors:
Antiretroviral therapy (ART) certainly has the potential to reduce HIV transmission, and the use of treatment as prevention is highly desirable.1 But the magnitude and durabilty of benefit of ART for prevention are unknown, and the provocative observational2 and ecological studies3,4 cited in Dr Montaner's and Hogg's correspondence do not offer such insight. We need to address 2 crucial issues as follows: (1) How should we advise HIV discordant couples about their transmission risk when the infected partner is receiving ART? (2) How do we develop a “test and treat” strategy" that reliably reduces incident cases of HIV.
Dr Wang Lu's article5 is important because it reflects on both of the above questions in the real world, not as the result of a controlled study or a modeling exercise. Her detection of HIV transmission from people provided ART does not negate the idea that lowering the viral load could reduce the per-contact probability of an HIV transmission event6; this is not an idea in dispute. But in the real world-for many reasons-people do not always experience continued and reliable suppression of HIV with ART (even in China where treatment and care are free). In the real world, people cannot monitor their viral load and STDs before sexual encounters; and suppression of HIV in blood frequently fails to prevent HIV replication and shedding in the genital tract.7
The success of the “test and treat strategy” requires that ART provided under real-world conditions-like in rural China or rural Africa-reliably and durably prevent transmission of HIV with reduction in new cases of HIV; Dr Wang Lu report highlights the obvious challenges we face as we try to harness ART as an HIV prevention modality.
Myron S. Cohen, MD
Institute of Global Health and Infectious Diseases The University of North Carolina at Chapel Hill Chapel Hill, NC
1. Cohen MS, Gay C. Treatment to prevent HIV transmission. Clin Infect Dis
. 2010;50:(Suppl 3):S85-S95.
2. Donnell D, Baeten JM, Kiarie J, et al. Heterosexual HIV-1 transmission antiretroviral therapy: a prospective cohort analysis. Lancet
3. Wood E, Kerr T, Marshall B, et al. Longitudinal community plasma HIV-1 RNA concentrations and incidence of HIV-1 among injecting drug users: prospective cohort study. BMJ
4. Montaner JS, Lima VD, Barrios R, et al. Association of highly active antiretroviral therapy coverage, population viral load, and yearly new HIV diagnoses in British Columbia, Canada: a population-based study. Lancet
5. Das, M, Cu PL, Santos GM, et al. Decreases in community viral load are accompanied by reductions in new HIV infections in San Francisco. PLoS One
6. Powers, KA, Poole, C, Pettifore AE, et al. Rethinking the heresosexual tramsission of HIV-1: A systematic review and meta-analysis. Lancet Infect Dis
7. Cu-Uvin S, Delong AK, Ventakesh KK, et al. Genital tract HIV-1 RNA shedding in women with below detectable plasma viral load. AIDS