Recently the first participants in the HVTN 702 study received jabs of a vaccine that could stop HIV in its tracks.
COMMENT
The goal of 90-90-90 by 2020 to ensure that globally 90% of people know their HIV status; 90% of those who test positive are on antiretroviral (ARV) treatment; and 90% of those who are on ARVs are no longer capable of transmitting HIV because the drugs are effectively suppressing the virus in their bodies. This will only be possible if the health systems of both rich and poor countries are reformed in such a way that no one is excluded, either because of their inability to pay or because of the stigma and discrimination that so often excludes those who are the most vulnerable.
Given the lack of universal health coverage, even in richer countries, it is fitting that reaching the 90-90-90 targets by 2020, and ending the Aids epidemic by 2030, as the United Nations aims to do, requires additional potent interventions that aim to stop the transmission of HIV in its tracks. These strategies need to be durable, should not rely on behaviour or adherence and they should be affordable for the poorest people.
An HIV vaccine would fit all these prescriptions, and even a modestly effective HIV vaccine, if scaled up and directed at young women in areas of the world with high HIV-infection rates, has the potential to slow the epidemic.
South Africa could be on the verge of such a breakthrough. In the past few weeks, the first 10 of 5 400 participants in a pivotal phase-three study, HVTN 702, received their jabs with either a placebo or HIV vaccine that is being tested. A phase-three study is the last stage of a clinical trial in which the efficacy of a product is tested on a relatively large number of people.
The HVTN 702 study is evaluating an HIV vaccine regimen adapted from the RV144 study conducted in Thailand, which showed modest vaccine efficacy. Since the release of the findings of the RV144 study in 2009, scientists around the world have been working together to adapt this vaccine regimen to the most common strain of HIV in Southern Africa. The vaccine components have also been modified to make the regimen more potent and durable than RV144.
HVTN 702 is a randomised control trial. In other words, about half of the participants receive a dummy vaccine and the other half get the vaccine that is being tested. It is being conducted at 15 sites in South Africa. The study will be carried out over 20 months, and the volunteers will be followed for 36 months so that by 2021 we will know whether this vaccine worked.
We will know this, and also how well it has worked, if the group who received the vaccine gets infected with HIV at a significantly lower rate than the participants who received the placebo vaccine. If successful, this could mean that by 2030 an HIV vaccine could be available in our region.
HVTN 702 will teach us many things about the immune system and what it takes to protect humans against HIV. If found to be efficacious, this HIV vaccine regimen could help us to make a much-needed dent in the epidemic.
We are cognisant that, since the beginning of the HIV epidemic, our efforts to manipulate the immune system to protect against HIV have, in the most part, not been successful. But we are seeing a change: we are entering a golden period of HIV research.
Besides HVTN 702, there are and will be many innovative vaccinology approaches emerging as we discover more and more about the structure of HIV. Technological advances that enable us to make better molecules capable of eliciting immune responses, also known as immunogens, are also helping us to move forward.
Already we are investigating the role of passively infused potent neutralising antibodies in curtailing HIV infection. Trials are ongoing in sub-Saharan Africa and the Americas to evaluate whether a potent neutralising antibody called VRC01 could prevent HIV infection in women and in men who have sex with men.
A locally discovered potent neutralising antibody from an HIV-infected woman in a study by the Centre for the Aids Programme of Research in KwaZulu-Natal is being developed to be evaluated in a cocktail of such antibodies.
In the next year, we will embark on a new proof of concept trial in women in sub-Saharan Africa using a different HIV vaccine approach. This has already shown promise in trials conducted among monkeys.
By evaluating all these approaches, we as scientists are safeguarding the dream that we have to give the world an HIV vaccine by 2030. The 90-90-90 goals will be realised by 2020 through the efforts of doctors and nurses, by health systems and by government commitment.
It will also be achieved by robust and durable prevention methods. An HIV vaccine would be a critical component of this, and a testament that science can triumph over a horrendous epidemic that has devastated our country in so many ways.
Professor Glenda Gray is the principal investigator of the HVTN 702 trial and the president of the South African Medical Research Council.
Glenda Gray is one of the lead co-investigators of South Africa’s Phase three B Sisonke study. Gray is the president of the South African Medical Research Council (SAMRC).
