In committed couples, HIV transmission from positive partners dropped from an expected incidence of more than 5% to less than 0.5% per year when the uninfected partner used pre-exposure prophylaxis (PrEP) for the first 6 months of the infected partner’s antiretroviral therapy, according to a study in PLOS Medicine.
The open-label demonstration project on which the study reports involved 1,013 heterosexual HIV-1–serodiscordant couples in Kenya and Uganda (PLOS Med. 2016 Aug 23. doi: 10.1371/journal.pmed.1002099).
Dr. Jared Baeten
“To our knowledge, this study is one of the first and one of the largest demonstration projects to provide PrEP to a priority population at risk for HIV-1 outside of a clinical trial setting, and the findings demonstrate the feasibility and impact of using PrEP as a bridging strategy to sustained HIV-1 protection by ART [antiretroviral therapy]” in serodiscordant couples, said investigators led by Jared Baeten, MD, of the department of global health at the University of Washington, Seattle. Wide-scale roll-out “could have substantial effects in reducing the global burden of new HIV-1 infections,” Dr. Baeten and his coauthors concluded.
PrEP kept uninfected partners safe until ART reliably suppressed viral loads at about 6 months. Adherence to the regimen was about 85%, which was higher than in some clinical trials, perhaps because couples were being offered “a strategy with demonstrated safety and efficacy” instead of unproven products and placebo. Couples also recognized their elevated HIV risk, the research team said.
It was good to find out that the approach works in real-world settings in Africa, Dr. Baeten and his associates said, where the majority of the 2 million people infected each year live. Follow-up was less frequent than in trials, with brief counseling sessions “equivalent to what would be expected in public health settings” and HIV tests about every 4 months over a median of about a year. “This study shows that a practical delivery approach ... can virtually eliminate HIV1- transmission,” the researchers said.
There were just two HIV transmissions in the study, both in women with self-reported and objective evidence of interrupted PrEP use. Overall, the transmission incidence was 0.2/100 person-years. The investigators estimated there would have been 40 transmissions – 5.2/100 person-years – without the intervention.
Couples were recruited by community outreach in four cities and towns – Kisumu and Thika in Kenya, and Kabwohe and Kampala in Uganda. The investigators targeted couples at high risk for transmission, including those reporting unprotected sex and infected partners with plasma HIV-1 RNA levels of 50,000 copies/mL or more.
Almost all were married and living together. They reported a median of six sex acts per month, many unprotected. Partners were a median of about 30 years old, and 67% of uninfected partners were men.
The preferred ART regimen was tenofovir disoproxil fumarate (TDF), lamivudine, and efavirenz, with zidovudine and nevirapine as alternatives. PrEP was a combination emtricitabine/TDF 200 mg/300 mg once daily; it was provided at the study sites since PrEP was otherwise unavailable in Kenya and Uganda.
The National Institutes of Health, Bill and Melinda Gates Foundation, and U.S. Agency for International Development funded the work. Gilead Sciences donated the TDF for PrEP. Dr. Baeten had no disclosures; another author reported funding from Gilead for a TDF pharmacokinetics study, and has a patent pending for a formulation different from the drug used in the study.