Prospects of elimination of HIV with test-and-treat strategy

Abstract

Recently, there has been much debate about the prospects of eliminating HIV from high endemic countries by a test-and-treat strategy. This strategy entails regular HIV testing in the entire population and starting antiretroviral treatment immediately in all who are found to be HIV infected. We present the concept of the elimination threshold and investigate under what conditions of treatment uptake and dropout elimination of HIV is feasible. We used a deterministic model incorporating an accurate description of disease progression and variable infectivity. We derived explicit expressions for the basic reproduction number and the elimination threshold. Using estimates of exponential growth rates of HIV during the initial phase of epidemics, we investigated for which populations elimination is within reach. The concept of the elimination threshold allows an assessment of the prospects of elimination of HIV from information in the early phase of the epidemic. The relative elimination threshold quantifies prospects of elimination independently of the details of the transmission dynamics. Elimination of HIV by test-and-treat is only feasible for populations with very low reproduction numbers or if the reproduction number is lowered significantly as a result of additional interventions. Allowing low infectiousness during primary infection, the likelihood of elimination becomes somewhat higher. The elimination threshold is a powerful tool for assessing prospects of elimination from available data on epidemic growth rates of HIV. Empirical estimates of the epidemic growth rate from phylogenetic studies were used to assess the potential for elimination in specific populations.

Why the proportion of transmission during early-stage HIV infection does not predict the long-term impact of treatment on HIV incidence

“…4B) (9,18). Eighty-six percent of the variation in the proportion of early transmission is explained by the reciprocal of R 0 (1/R 0 ; red line in Fig.…”

“…The model is calibrated to longitudinal HIV prevalence data from South Africa using a Bayesian framework. Thus, the model accounts for not only the early epidemic growth rate highlighted in previous research (5,9,18), but also the heterogeneity and sexual behavior change to explain the peak and decline in HIV incidence observed in sub-Saharan African HIV epidemics (32,33).…”

“…One concern is that if a large fraction of HIV transmission occurs shortly after a person becomes infected, before the person can be diagnosed and initiated on ART, this will limit the potential impact of HIV treatment on reducing HIV incidence (9,17,18). Data suggest that persons are more infectious during a short period of "early infection" after becoming infected with HIV (19-22), although there is debate about the extent, duration, and determinants of elevated infectiousness (18, 23).…”

“…This finding has generated interest in understanding the population-level impact of HIV treatment on reducing the rate of new HIV infections in generalized epidemic settings (4). Research, including mathematical modeling (5-10), implementation research (11), and major randomized controlled trials (12)(13)(14), are focused on how ART provision might be expanded strategically to maximize its public health benefits (15, 16).One concern is that if a large fraction of HIV transmission occurs shortly after a person becomes infected, before the person can be diagnosed and initiated on ART, this will limit the potential impact of HIV treatment on reducing HIV incidence (9,17,18). Data suggest that persons are more infectious during a short period of "early infection" after becoming infected with HIV (19-22), although there is debate about the extent, duration, and determinants of elevated infectiousness (18, 23).…”

Antiretroviral therapy for prevention of HIV transmission: implications for Europe

“…Modelling studies have explored the widespread use of ART but mainly in sub-Saharan settings [72][73][74][75][76][77][78][79][80][81][82][83][84][85][86][87][88][89], in the United States [90;91], in China [92][93][94], Canada [95] and for some specific groups, such as MSM in Australia [36;96;97], in Peru, Ukraine, Kenya and Thailand [98] and in different cities in the United States [99][100][101][102][103]; only a few of them model the HIV epidemic in European countries (MSM in Amsterdam, the Netherlands [104] and in the UK [105][106][107] and people who inject drugs in Russia [108]). They varied in their conclusions, although most have suggested potential appreciable beneficial effects on HIV incidence of introducing ART initiation at a higher CD4 count as a policy at a population level.…”