"[This study] will tell us whether the initial success observed [at a smaller scale] will bear fruit in the form of a safe and effective HIV vaccine designed for the people of southern Africa," said Glenda Gray said, head of South Africa's Medical Research Council.
In the Thai study, the HIV vaccine was 31.2 percent effective at preventing HIV infection. This rate of success was deemed modest, since it spanned over 3.5 years after vaccination. Nevertheless, researchers remain optimistic that any positive effects, even if modest, can improve the situation significantly. “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 Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases (NIAID).
The current vaccine has 2 components: a canarypox vector-based vaccine called ALVAC-HIV, and a gp120 protein subunit vaccine to augment the body’s immune response. Because this treatment does not contain HIV itself, there is no risk of contracting HIV from the vaccines. Furthermore, the HVTN 702 vaccine has been modified to be specific to the HIV subtype C found in Southern Africa.
It is not by chance that the biggest HIV vaccine trial is being conducted in South Africa. This part of the world sees more than 1,000 new HIV infections everyday. “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,” said Gray.
Participants in the study will be randomized to receive either the vaccine or the placebo. Both groups will receive 5 injections over the course of 1 year, along with standard HIV prevention education. Should participants contract HIV, they will be referred to treatment facilities in accordance with standard practice. Though everyone is optimistic, the results will not be known for a few more years. Still, this trial is a landmark attempt at combatting HIV, and we are sure to learn much from this study.
Additional sources: NIH, BBC