NIH Launches First New HIV Vaccine Efficacy Study in 7 Years in South Africa

The biggest HIV clinical trial that South Africa has seen has launched and it is the first HIV vaccine efficacy study in seven years.

The efficacy study, dubbed HVTN 702, seeks to test if a vaccine regimen can effectively provide adults with adequate protection against HIV. The vaccine is a newer version of RV144, the only vaccine candidate that has, thus far, provided some protection against the virus, one that affects 1.2 million people in the United States alone, each year.

Currently, 1,000 people become infected with HIV every day in South Africa. Due to these troubling numbers, an effective vaccine has long been sought after by researchers. Piggybacking off of the vaccine regimen that had been used in the RV144 trial headed by the US Military HIV Research Program in Thailand, the new regimen aims to provide a better level of protection that lasts for a longer period of time. In addition, the new vaccine regimen is specific to HIV subtype C, the one that is most prevalent in South Africa.

Enrollment for HVTN 702, conducted by the HIV Vaccine Trials Network (HVTN), started on October 26, 2016, and researchers hope to enroll 5,400 sexually active men and women between the ages of 18 and 35 years. The trial will be conducted at 15 different sites located in the following provinces: Guateng, KawZulu-Natal, North West, Eastern Cape, and Western Cape. The participants will receive five injections over the course of a year of either the vaccine regimen or a placebo.

Where the RV144 trial proved to be only 31.2% effective in its preventive capabilities, the Phase 2b/3 trial strives to provide even greater means of protection. According to the press release, “In the HVTN 702 study, the design, schedule and components of the RV144 vaccine regimen have been modified in an attempt to increase the magnitude and duration of the vaccine-elicited protective immune responses.”

The new vaccine regimen is comprised of ALVAC-HIV, a canarypox vector-based vaccine, and “a two-component gp120 protein subunit vaccine with an adjuvant to enhance the body’s immune response to the vaccine.” The adjuvant, MF59, is a different one than the one that had been used in the RV144 study. The researchers hope that this adjuvant may incite a stronger immune system response than the one that had been used in the previous study. With booster shots at “the one-year mark” also included in the new vaccine regimen, researchers hope to lengthen the time of protection from the virus.

In the official press release, Anthony S. Fauci, MD, director of the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health and co-funder of the trial commented, “If deployed alongside our current armory of proven HIV prevention tools, a safe and effective vaccine could be the final nail in the coffin for HIV. Even a moderately effective vaccine would significantly decrease the burden of HIV disease over time in countries and populations with high rates of HIV infections, such as South Africa.”

Through monitoring, researchers will continually assess the safety of the participants. In addition, all participants will be given the standard of care for HIV prevention; this means that they will receive condoms and counseling to become more aware of behavior that can put them at risk of infection. The participants will also have the opportunity to receive pre-exposure prophylaxis, or PrEP, due to the fact that the HVTN 702 vaccine regimen had been designed so that researchers could still measure how effective the vaccine is in providing protection from the virus despite PrEP. Those who become infected with HIV will receive treatment from local medical providers through referral.

HVTN 702 Protocol Chair Glenda Gray, MBBCH, FCPaed, said in the press release, “The people of South Africa are making history by conducting and participating in the first HIV vaccine efficacy study to build on the results of the Thai trial. HIV has taken a devastating toll in South Africa, but now we begin a scientific exploration that could hold great promise for our country. If an HIV vaccine were found to work in South Africa, it could dramatically alter the course of the pandemic.”

HVTN 702 is one of the many efforts that NIAID has taken part in during the ongoing fight against HIV. Other preventive efforts include: AMP Studies, which is examining VRC01 antibody infusions, the HOPE study, which is testing a dapivirine vaginal ring, HPTN 076, which is examining injectable rilpivirine, and HPTN 077, which is studying injectable cabotegravir.