Factors behind rise in HIV in men who have sex with men

18 February 2013

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Between 1990 and 2010 new HIV infections in the UK rose in men who have sex with men (MSM). The rise was driven by a 26 per cent increase in the proportion having condomless sex, according to new research by UCL and the Health Protection Agency.

However, the findings suggest the increase in new infections would have been 68 per cent greater without the introduction of antiretrovirals (ART) in the same period, and 400 per cent greater if MSM condom use had ceased entirely from 2000 onwards.

Lead investigator Professor Andrew Phillips (UCL Infection and Immunity) said: “We created a model reconstructing the HIV epidemic in men who have sex with men in the UK. In doing so, we were able to explore the interplay between HIV testing rates, antiretroviral treatment and sexual behaviour on HIV transmission and incidence. By better understanding the driving forces behind the trends we’ve seen in the past, it will allow us to make informed choices to reduce new HIV infections in the future.”

By creating a model we were able to explore the interplay between HIV testing rates, antiretroviral treatment and sexual behaviour on HIV transmission and incidence.

Professor Andrew Phillips, UCL Infection and Immunity

Dr Valerie Delpech, head of HIV surveillance at the HPA, said: “Our research provides important evidence to support current UK public health recommendations on expanded HIV testing and higher levels of ART coverage, to reduce new infections among men who have sex with men.

"However, we see it is also vital condom use education continues as not only does this have a strong limiting effect on the HIV epidemic, but only a modest increase in unprotected sex is enough to erode the benefits of other interventions.”

Estimated HIV incidence rose from 0.30 per 100 person years (1990-1997) to 0.53 (2006-2010), associated with increased condomless sex following the introduction of effective ART.

However, exploring other scenarios, the research found incidence would have reduced during this period if HIV testing levels had been higher (25 per cent lower incidence), if ART had been prescribed at diagnosis (32 per cent lower incidence) or these interventions had been combined (62 per cent lower incidence). Effective ART therapy reduces the infectivity of HIV positive individuals, lowering transmission risk.

Dr Delpech, HPA, continued: “Everyone should use a condom when having sex with new or casual partners, until all partners have had a sexual health screen. We also encourage men who have sex with men to get an HIV and STI screen at least annually, and every three months if having condomless sex with new or casual partners – and clinicians to take every opportunity to recommend HIV testing to this group.

"Through combining earlier and more frequent HIV testing, programmes that reduce unsafe sexual behaviour and higher levels of ART coverage for those requiring it, we could substantially reduce HIV transmission in this group.”

Published in PLOS ONE, the study received funding from the National Institute for Health Research.

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Media contact: Dave Weston


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