Background: Antiretroviral therapy (ART) used by HIV infected individuals and pre-exposure prophylaxis (PrEP) by HIV uninfected individuals are highly efficacious HIV prevention tools. Assessing the effectiveness of these interventions and integrated delivery strategies in implementation settings is a priority.
Methods: The Partners Demonstration Project, an open-label PrEP and ART delivery study, began in 2012, and enrolled antiretroviral-naïve, high-risk, heterosexual HIV serodiscordant couples from Kenya and Uganda. Couples were followed for 2 years. ART was recommended following national ART guidelines - initially CD4 < 350 cells/µL but soon thereafter all HIV serodiscordant couples regardless of CD4 count. PrEP was offered as a ''bridge'' to ART in the partnership - i.e., until ART initiation by the HIV infected partner and for the first 6 months after ART initiation. We compared observed HIV incidence to a counterfactual simulation model, using bootstrapping methods and constructed with data from a prior prospective study of HIV serodiscordant couples (the Partners PrEP Study, placebo arm). In a previously reported interim analysis, with ~40% of total expected follow-up time accrued, we found that HIV incidence was substantially reduced (2 incident infections compared to 40 expected infections); updated findings are presented here.
Results: Of 1,013 couples enrolled, 67% had an HIV positive female partner and the median age was 29. Among a randomly-selected sample of HIV negative partners receiving PrEP, tenofovir was detected in 82% of plasma samples (483/587 visits). ART was initiated by 92% of HIV positive partners by 24 months and viral suppression (< 400 copies/mL) was achieved in 90%. As of January 2016, counterfactual simulations predicted that 63 incident HIV infections would be expected (incidence rate 5.1 per 100 person years, 95% CI 3.9-6.4). However, only 5 incident infections have been observed (incidence rate 0.3, 95% CI 0.1-0.7), for sustained HIV relative risk reduction of 94% (95% CI 85-98, p< 0.001).
Conclusions: An integrated PrEP and ART strategy is highly effective for preventing HIV transmission within HIV serodiscordant couples, showing near elimination in a high risk cohort. The Partners Demonstration Project will complete follow-up and analysis in June 2016 with final results available in July 2016.