Experimental HIV vaccine trial stopped after jab found ineffective

South Africa will halt one of the largest and most advanced HIV vaccine trials ever to be undertaken in the country ahead of schedule after the jab was found to be safe but not effective at protecting against HIV infection.

In 2016, South African researchers embarked on the HVTN 702 study - what they thought might just be the best shot at developing a vaccine to protect people from HIV infection. At the centre of the research? The world's only experimental HIV jab to ever show a modest result - too modest a result, showed the 2009 results of a Thai trial published in the New England Medical Journal, however for the vaccine to make it to market.

But in South Africa, the vaccine had been packed with a new adjuvant which is an ingredient used to stimulate immune system responses. It had a new booster and had been specially formulated for the HIV strains most common to South Africa. 

"The fact remains that the HIV epidemic is still really, in many respects, out of control and South Africa has more infections than essentially any other country," said Anthony Fauci at the time. Fauci heads the United States government's National Institutes of Allergy and Infectious Diseases (NIAID), which funded the trial. 

He reasoned: "A safe and effective vaccine could be the final nail in the coffin for HIV."


Late on Monday, researchers announced that almost four years later, they will stop administering the jab to the 5 400 people who enrolled in the trial at 14 sites across South Africa.

The decision comes after a review of data from almost 5 400 participants found the shot had been unsuccessful in preventing new HIV infections.

As part of the trial, HIV-negative people at 14 sites across the country agreed to receive six shots over 18 months - half of whom will get the vaccine while the other 50% receive a placebo as part of a randomised controlled clinical trial. 

This kind of randomisation means that any characteristics such as age or location that could have a bearing on the study's outcome should be equally present in both groups. Studies designed in this way - also called randomised controlled clinical trials - are better at determining cause and effect than other types of studies and are often called the "gold standard" in research.

But early results in January showed that whether groups of participants got the real shot or the fake, each cluster - or arm - of the study showed roughly the same number of new infections.  

Well-conducted trial

In short, said the NIAID, there was no difference in the risk of contracting HIV between those that got the vaccine and those who didn't.

"We always hope that efficacy trials will show positive results that lead to new prevention options," explained Avac executive director Mitchell Warren in a statement. "It is very disappointing that this vaccine candidate does not work, but the trial was well-conducted and got an answer as quickly as possible."

Scientists will continue to follow up with participants for up to a year, deputy director of the Desmond Tutu HIV Foundation and one of the lead researchers Linda-Gail Bekker told Bhekisisa. She explained that the trial stopped injections at all sites Monday. 

Participants will get letters asking them to urgently come to their nearest research clinic for more information on the results. 

The trial is just one of three different HIV vaccine studies ongoing in South Africa - each taking a slightly different approach at trying to ward off new infections. Tuesday's announcement about HVTN 702 study does not affect the other two trials.

Valuable contribution

Glenda Gray is the president of South Africa's Medical Research Council and one of the trial's lead researchers. In a statement, she said that regardless of the results, the trial - and the people involved - had still made a valuable contribution to science.  

"The people of South Africa have made history by answering an important scientific question," said Glenda Gray. "We will continue to explore promising avenues for preventing HIV with other vaccines and tools, both in South Africa and the world."

Vaccine activist organisation, the Vaccine Advocacy Resource Group (Varg) called the news disheartening but it too believed that the trial had provided valuable data to the “ever-increasing pool of knowledge along the road to find a vaccine for HIV.” 

In a statement, Varg said the trial was a reminder of the need “to push for meaningful, and honest engagement and transparency, which is critically lacking in far too many trials.” 

“We centre, we salute and we honour the 5 400 mostly black South Africans who made this trial possible.”

This story was produced by the Bhekisisa Centre for Health Journalism, http://bhekisisa.org. Subscribe to the newsletter http://bit.ly/BhekisisaSubscribe

Image credit: iStock

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