Research ArticleHIV

Sources of HIV infection among men having sex with men and implications for prevention

Science Translational Medicine  06 Jan 2016:
Vol. 8, Issue 320, pp. 320ra2
DOI: 10.1126/scitranslmed.aad1863

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The ART of HIV prevention

Despite the relative success of antiretroviral therapy (ART) for individuals infected with HIV, the rate of new diagnoses has remained fairly constant in vulnerable population groups, particularly men having sex with men (MSM). Now, ART is also available in the United States to uninfected individuals to directly prevent infection with the virus. Ratmann et al. were able to reconstruct ~600 past transmission events among men having sex with men in the Netherlands, and examined probable sources of transmission. They found that the large majority of new infections is neither attributable to ineffective ART nor inadequate retention in care. Rather, many of these cases could have been averted with more comprehensive HIV testing and a broader use of ART that includes provision to uninfected men as well as starting ART as soon as possible among newly diagnosed men. These findings support making ART for pre-exposure prophylaxis available worldwide, and especially in countries with high retention in care and high ART coverage among infected MSM.

Abstract

New HIV diagnoses among men having sex with men (MSM) have not decreased appreciably in most countries, even though care and prevention services have been scaled up substantially in the past 20 years. To maximize the impact of prevention strategies, it is crucial to quantify the sources of transmission at the population level. We used viral sequence and clinical patient data from one of Europe’s nationwide cohort studies to estimate probable sources of transmission for 617 recently infected MSM. Seventy-one percent of transmissions were from undiagnosed men, 6% from men who had initiated antiretroviral therapy (ART), 1% from men with no contact to care for at least 18 months, and 43% from those in their first year of infection. The lack of substantial reductions in incidence among Dutch MSM is not a result of ineffective ART provision or inadequate retention in care. In counterfactual modeling scenarios, 19% of these past cases could have been averted with current annual testing coverage and immediate ART to those testing positive. Sixty-six percent of these cases could have been averted with available antiretrovirals (immediate ART provided to all MSM testing positive, and preexposure antiretroviral prophylaxis taken by half of all who test negative for HIV), but only if half of all men at risk of transmission had tested annually. With increasing sequence coverage, molecular epidemiological analyses can be a key tool to direct HIV prevention strategies to the predominant sources of infection, and help send HIV epidemics among MSM into a decisive decline.

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