Low transmission if couples both receiving ART and PrEP

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Providing HIV medication to both members of a couple may substantially reduce the risk of transmission within that couple, according to a University of Washington study.

Jared Baeten of the University of Washington and colleagues conducted a prospective implementation study to test the feasibility and acceptability of a programme to initially offer antiretroviral medications to both members of couples in which one member was HIV-positive and the other was HIV-negative (HIV-serodiscordant couples).

The researchers enrolled 1,013 heterosexual HIV-serodiscordant couples in Kenya and Uganda who were at high risk of transmission based on behavioural and biological characteristics. Antiretroviral therapy (ART), which by suppressing HIV replication both controls progression of HIV and reduces infectiousness, was provided to the HIV-infected partner. To reduce susceptibility to infection prior to viral suppression in the HIV-infected partner, the HIV-uninfected partners were offered antiretroviral drugs for pre-exposure prophylaxis (PrEP) prior to and during the first 6 months of ART.

The researchers followed the couples for an average of about one year per couple. The primary goals of the study were to evaluate implementation of this delivery model, however, part-way through the anticipated delivery period, it became clear that HIV transmission rates were considerably lower than would have been anticipated. In addition to high acceptability and adherence, the dual treatment regimen showed rates of HIV transmission 96% lower than estimated rates of transmission in a simulated cohort of serodiscordant couples.

The researchers note that conclusions are limited because this study does not include a concurrent comparison population for HIV transmission, as it would not have been ethical to enrol a control population and not offer access to ART and PrEP. Nevertheless, the findings suggest this may be a promising strategy for in the fight to reverse the HIV epidemic.

The authors say: “The results of this project demonstrate that an integrated strategy of ART and PrEP can be delivered feasibly to a high-risk African population and result in almost complete protection from HIV-1 transmission.”

Abstract
Background: Antiretroviral-based interventions for HIV-1 prevention, including antiretroviral therapy (ART) to reduce the infectiousness of HIV-1 infected persons and pre-exposure prophylaxis (PrEP) to reduce the susceptibility of HIV-1 uninfected persons, showed high efficacy for HIV-1 protection in randomized clinical trials. We conducted a prospective implementation study to understand the feasibility and effectiveness of these interventions in delivery settings.
Methods and Findings: Between November 5, 2012, and January 5, 2015, we enrolled and followed 1,013 heterosexual HIV-1-serodiscordant couples in Kenya and Uganda in a prospective implementation study. ART and PrEP were offered through a pragmatic strategy, with ART promoted for all couples and PrEP offered until 6 mo after ART initiation by the HIV-1 infected partner, permitting time to achieve virologic suppression. One thousand thirteen couples were enrolled, 78% of partnerships initiated ART, and 97% used PrEP, during a median follow-up of 0.9 years. Objective measures of adherence to both prevention strategies demonstrated high use (≥85%). Given the low HIV-1 incidence observed in the study, an additional analysis was added to compare observed incidence to incidence estimated under a simulated counterfactual model constructed using data from a prior prospective study of HIV-1-serodiscordant couples. Counterfactual simulations predicted 39.7 HIV-1 infections would be expected in the population at an incidence of 5.2 per 100 person-years (95% CI 3.7–6.9). However, only two incident HIV-1 infections were observed, at an incidence of 0.2 per 100 person-years (95% CI 0.0–0.9, p < 0.0001 versus predicted). The use of a non-concurrent comparison of HIV-1 incidence is a potential limitation of this approach; however, it would not have been ethical to enroll a contemporaneous population not provided access to ART and PrEP.
Conclusions: Integrated delivery of time-limited PrEP until sustained ART use in African HIV-1-serodiscordant couples was feasible, demonstrated high uptake and adherence, and resulted in near elimination of HIV-1 transmission, with an observed HIV incidence of <0.5% per year compared to an expected incidence of >5% per year.

Authors
Jared M Baeten, Renee Heffron, Lara Kidoguchi, Nelly R Mugo, Elly Katabira, Elizabeth A Bukusi, Stephen Asiimwe, Jessica E Haberer, Jennifer Morton, Kenneth Ngure, Nulu Bulya, Josephine Odoyo, Edna Tindimwebwa

PLOS material
PLOS Medicine abstract


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