Immediate antiretroviral treatment as a strategy for controlling the HIV epidemic amongst men having sex with men
A. van Sighem1, D. Bezemer1, G. Garnett2, F. de Wolf1,2, C. Fraser2
1Stichting HIV Monitoring, Amsterdam, Netherlands, 2Imperial College School of Medicine, London, United Kingdom
Background: The HIV epidemic in the Netherlands amongst men having sex with men (MSM) is near the epidemic threshold. We investigated the impact of starting combination antiretroviral treatment (cART) immediately at diagnosis on top of other interventions as a strategy to control the epidemic.
Methods: Within-country transmission rates, diagnosis rates, and annual number of infections needed to explain observed national data on HIV and AIDS diagnoses amongst MSM were estimated by fitting a mathematical model. Besides immediate treatment, two other intervention strategies were explored:
(1) reducing overall risk behaviour to levels estimated in the years before the cART era,
(2) reducing the average time between infection and diagnosis from 2.5 to 0.5 years in combination with a 50% decrease in risk behaviour after diagnosis Their effect was quantified by the cumulative number of infections between 2010 and 2020.
Results: Without any interventions the number of new infections from 2010 to 2020 was predicted to be 11,274. Immediate treatment as the only intervention yielded 7676 (-32%) predicted new infections. Reducing the time to diagnosis to 0.5 years gave 5848 (-48%) new infections. When earlier diagnosis was combined with immediate treatment, the number of infections was reduced to 4340 (-39% compared to earlier diagnosis as only intervention) and 3524 (-40%), respectively. Reducing transmission rates back to pre-cART levels combined with immediate treatment and a time to diagnosis of 2.5 years yielded 2484 new infections, a reduction of -18% compared to 3027 infections with lower transmission rates as only intervention.
Conclusion: Reducing overall risk behaviour, and, to a lesser extent, earlier diagnosis gives the largest reduction in the HIV epidemic amongst MSM over the coming decade. Immediate treatment reduces the epidemic by 20-40% and has to be employed in combination with other interventions in order to be an effective intervention strategy.