IN WHAT could be the world’s best hope of ending the HIV/Aids epidemic, the largest and most advanced HIV vaccine clinical trial to take place in South Africa is now under way at research centres nationwide.
On Wednesday, some of the first of 5 400 volunteers to be enrolled in the study, called HVTN 702, received their initial injections. HVTN 702 will establish whether an experimental vaccine regimen safely prevents HIV infection among South African adults.
It involves a new version of the only HIV vaccine candidate yet shown to provide some protection against the virus and is being conducted solely at 15 research centres in South Africa.
Principal investigator at the HIV Vaccine Trials Network (HVTN) Dr Larry Corey said: “This launch represents a significant HIV prevention milestone. In earlier studies, this vaccine regimen improved on many of the antibody responses to the types of HIV strains circulating in South Africa, providing us the scientific basis to conduct this pivotal trial. This study will provide important insights into vaccine development to help prevent new infections and end the epidemic.”
The experimental vaccine regimen being tested in HVTN 702 is based on the one investigated in the RV144 clinical trial in Thailand led by the US Military HIV Research Programme and the Thai Ministry of Health. The Thai trial delivered landmark results in 2009 and the experimental vaccine regimen it tested was found to be 31.2 percent effective in preventing HIV infection over the 3.5-year follow-up period after vaccination.
In the HVTN 702 study, the design, schedule and components of the RV144 vaccine regimen have been modified to increase the magnitude and duration of the protective immune responses elicited by the vaccine.
Funding the R1.6 billion trial is the National Institute for Allergy and Infectious Diseases, the Bill & Melinda Gates Foundation, and the South African Medical Research Council (MRC). The 5 400 study volunteers are being randomly assigned to receive either the investigational vaccine regimen or a placebo. All study participants will receive injections on five occasions over one year.
Protocol co-chair of HVTN 702 and deputy director of the Desmond Tutu HIV Centre Linda-Gail Bekker said: “Because we have the benefit of building on the Thai study, this is probably the best shot we have ever had. We are going to keep building on this, so whatever result we get at the end of the study, we will learn an enormous amount that will be ploughed back into the vaccine field.”
She said this kind of clinical research is critical to move the field forward. “I’m hugely hopeful. We are very optimistic. There is a good sense that we’ve mustered the best minds, the best science... however, the science must play out,” Bekker said.
Director of the Division of Aids in the US's National Institute for Allergy and Infectious Diseases Dr Carl Dieffenbach said trial success would mean an efficacy rate of about 60 percent. “Today is a day of hope. This is the beginning of the next phase of our journey in the search for a safe, effective and durable HIV vaccine. It started years ago with many studies that fundamentally failed,” he said.
Dieffenbach said the vaccine has been brought to SA to be evaluated where the epidemic is most intense. “The vaccine needs to work here and then we can take what we learn and go global with it.”
HVTN 702 protocol chair and president and MRC chief executive Professor Glenda Gray said if an HIV vaccine is found to work in South Africa, it could dramatically alter the course of the epidemic. “HIV has taken a devastating toll in South Africa – and we are still seeing about 1 000 new infections every day – but we now begin a scientific exploration that could hold great promise for our country,” Gray said.
HVTN 702 begins just months after interim results were reported for HVTN 100, a smaller clinical trial, which found that the new vaccine regimen was safe for the 252 study participants and induced comparable immune responses to those reported in RV144.
HVTN 100 participant Launa Jack from Crossroads said she volunteered for the study in the hope that she could contribute to ending the HIV/Aids epidemic. The 21-year-old said: “I want our country to be a healthy country, I want HIV to come to an end. Together we can do that. My family is very supportive, they understand. They are happy and proud for me to join a study that will prevent me from getting this infection.”