Current and forthcoming studies of vaccines to prevent HIV infection were presented at the ongoing 21st International AIDS Conference (AIDS 2016) in Durban.
These included information on advances in the development of novel vaccines, and in the field of antibody mediated prevention (AMP), it was revealed at the conference on Tuesday.
Interim immunology results open the way for the first major HIV vaccine efficacy study in seven years, scientists say.
Participants at AIDS 2016 heard results from the HVTN 100 study, conducted by the US-based HIV Vaccine Trails Network (HVTN) in partnership with South African research sites.
HVTN 100 tested the immune responses of South African study volunteers to a modified version of the RV144 regimen, the only HIV vaccine regimen to show efficacy to date.
The original RV144 vaccine reduced the HIV infection rate among study participants in Thailand by 31 percent over 3.5 years.
"HVTN 100 used the same vaccines that RV144 tested, but made them specific to the Clade C subtype of HIV, which is widespread in Southern Africa. We also changed the adjuvant used with one of the vaccines, with the goal of eliciting a more powerful immune response, and added a booster injection to prolong the period of protection," said HVTN 100 Protocol Chair Linda-Gail Bekker, who is also Deputy Director of the Desmond Tutu HIV Centre in Cape Town and International AIDS Society President-Elect.
HVTN 100 provides the green light for a Phase III efficacy trial on the modified RV144 regimen. Criteria for the go-ahead centred on the percentage of HVTN 100 vaccine-recipients who displayed a range of immune responses, and the strength of those responses.
"All the criteria were met unequivocally and, in many instances, the HVTN 100 outcomes exceeded both our own criteria and the immune responses seen in RV144," Bekker said.
Larry Corey, HVTN Principal Investigator, elaborated: "It is gratifying to see vaccines that were designed and manufactured specifically for South Africa meet and even exceed the criteria established to advance them into the large efficacy trial. HVTN 702 is a pivotal study that could lead to a licensed HIV vaccine in South Africa, the first preventive HIV vaccine worldwide."