HIV Vaccine Trial Launches in South Africa

Still in the midst of a world-wide HIV pandemic, scientists have shifted their focus to a vaccine that didn’t work seven years ago.

But that vaccine did prove that HIV prevention is achievable.

This is the first HIV vaccine clinical study to launch in seven years. Called the HVTN 702 study, results are expected in late 2020.

"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," said Anthony S. Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases (NIAID).

"Even a moderately effective vaccine would significantly decrease the burden of HIV disease over time in countries and populations with high rates of HIV infection, such as South Africa," said Dr. Fauci.

The experimental vaccine regimen being tested, HVTN 702, is based on the one investigated in the RV144 clinical trial in Thailand led by the U.S. Military HIV Research Program and the Thai Ministry of Health.

The Thai trial delivered landmark results in 2009 when it found for the first time that a vaccine could prevent HIV infection. This experimental vaccine found to be 31.2 percent effective at preventing HIV infection over the 3.5-year follow-up after vaccination.

The new regimen aims to provide greater and more sustained protection than the RV144 regimen and has been adapted to the HIV subtype that predominates in southern Africa, a region that includes the country of South Africa.

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 vaccine-elicited protective immune responses.

The HVTN 702 vaccine regimen consists of two experimental vaccines: a canarypox vector-based vaccine called ALVAC-HIV and a two-component gp120 protein subunit vaccine with an adjuvant to enhance the body's immune response to the vaccine.

The vaccines do not contain HIV and therefore do not pose any danger of HIV infection to study participants. Both ALVAC-HIV (supplied by Sanofi Pasteur) and the protein vaccine (supplied by GSK) have been modified from the versions used in RV144 to be specific to HIV subtype C, the predominant HIV subtype in southern Africa.

Additionally, the protein subunit vaccine in HVTN 702 is combined with MF59 (also supplied by GSK), a different adjuvant than the one used in RV144, in the hope of generating a more robust immune response.

Finally, the HVTN 702 vaccine regimen includes booster shots at the one-year mark in an effort to prolong the early protective effect observed in RV144.

HVTN 702 is one of many NIAID-supported HIV prevention trials in progress in southern Africa. These include the AMP Studies, which are testing infusions of the VRC01 antibody; the open-label HOPE study, which is examining a dapivirine vaginal ring; and HPTN 076 and 077, which are studying long-acting injectable rilpivirine and cabotegravir, respectively.

NIAID conducts and supports research--at NIH, throughout the United States, and worldwide--to study the causes of infectious and immune-mediated diseases, and to develop better means of preventing, diagnosing and treating these illnesses.