In this proposal we aim to investigate whether elimination is feasible at all in MSM populations and if so, what intervention effort is required for achieving elimination of HIV. We have developed a theoretical framework that allows the combination of information from HIV natural history and estimates of epidemic growth rates to assess whether, and under what circumstances, elimination is feasible amongst MSM in NL.

The main research question of this proposal is to assess whether information from the early phase of the HIV epidemic – in particular genetic sequence information - in combination with estimates of treatment and intervention effects over time can be used to assess elimination prospects in men who have sex with men (MSM).
Specific subquestions are:
• Can we use molecular sequence data to estimate the transmission potential as quantified by the basic or effective reproduction number of HIV in specific populations?
• What other epidemiological measures besides the exponential growth rate can be derived from sequence data that would help us assess the present transmission potential as it is modified by intervention measures in the past?
• What is the influence of heterogeneity in partner change rates and partnership duration in determining elimination prospects? What is the effectiveness of targeting treatment to specific high risk groups?
• How are elimination prospects affected by differing levels of prevalence of resistant HIV strains for which reduction of viral loads by combination antiretroviral therapy (cART) is less than for sensitive strains?
• Would pre-exposure prophylaxis with antiretrovirals (PreP, another intervention that influences viral load) be a useful additional measure to improve elimination prospects and at what scale would it need to be applied?

The results will give insight in whether or not elimination is feasible in the long run amongst MSM in NL

scientific community
policy makers

Recently there has been much debate about the prospects of eliminating HIV from high endemic countries by a “test and treat” strategy (Granich et al 2009). The rationale behind the test and treat approach is that offering regular HIV testing to entire populations and starting antiretroviral treatment immediately in all those found to be HIV positive reduces their viral loads to undetectable levels and therefore the probability of onward transmission is reduced to very low levels.
Test and treat is now one of a group of strategies being assessed for the population level benefits of antiretroviral ‘treatment as prevention.’ Pre-exposure prophylaxis (PreP) with antiretrovirals taken by HIV-uninfected people to prevent acquisition of infection also uses treatment as prevention.

Recently, ”test and treat” has been put forward as a strategy that might lead to elimination of HIV, the rationale being that early identification and treatment of infected persons should reduce transmission rates.
To judge the prospects of eventual elimination, we need to know whether or not incidence will decrease to zero in the long term at realistic levels of uptake and sustainability. In addition, the findings of cost-effectiveness studies are sensitive to assumptions about whether or not elimination is feasible in the long run.
Mathemathical modelling could give more insight in this.