One of the HIV vaccine efficacy studies is stopped due to non-efficacy

Cape Town | HVTN 702/Uhambo, one of the three HIV vaccine efficacy studies, underway in South Africa has been stopped early. This decision comes after an independent data and safety monitoring board (DSMB) found during an interim review that the regimen was not effective in preventing HIV. Uhambo was the world’s first HIV vaccine efficacy study conducted in South Africa since 2009.

South Africa faces one of the biggest HIV epidemics in the world with an estimated 7.7 million people living with HIV in 2018. According to data from UNAIDS, more than 20% of the adult population ages 15-49 years are living with HIV, and 240,000 people acquired HIV in 2018. Young people between the ages of 15-24 years are particularly at risk, with men who have sex with men, transgender women, sex workers and people who inject drugs experience even higher HIV prevalence rates.

Uhambo was launched to test whether an experimental vaccine regimen could safely prevent HIV infection among adults in South Africa. The study built on an earlier trial in 2009 called RV144 conducted in Thailand with over 16,000 people. The results from RV144 were promising, showing the vaccine prevented 31.2% of new HIV infections. Based on this, an international scientific effort adapted the regimen to be more specific to the circulating clades in southern Africa.

Uhambo, which means “journey” set out to find out whether this HIV vaccine regimen could protect people from HIV. “The people of South Africa have made history by answering this important scientific question. Sadly, we wish the answer was different,” said Prof Glenda Gray, President and CEO of the SAMRC and HVTN 702 Protocol Chair. “We will continue with our HIV vaccine programmes and other promising avenues for preventing HIV, both in South Africa and around the world,” says Gray.

The Uhambo study enrolled 5,407 HIV-negative participants at 14 sites across South Africa, consisting of sexually active women and men aged 18 to 35 years. “We are deeply indebted to the many participants who walked the journey with us in the Uhambo study, the results are not what we hoped for, but we value the continued support of other efficacy studies,” said Dr Mookho Malahleha, one of the Protocol Co-Chairs, from the Setshaba Research Centre, in Soshanguve, Gauteng.

The DSMB commended the HVTN protocol team on their effort in conducting the trial, as well as the study team’s high regard for the participants in the trial. The study team shares its gratitude to the participants and partners whose leadership were integral to this study and the pursuit of an HIV vaccine. “We commend all the research sites, the South African communities and each participant for their tireless commitment to finding solutions to the HIV epidemic,” added HVTN 702 Protocol Co-Chair, Prof Linda-Gail Bekker, from the Desmond Tutu HIV Foundation in Cape Town, South Africa.

The study volunteers were randomly assigned to receive either the investigational vaccine regimen or placebo injections. Six injections were administered to study participants over the course of 18 months. The safety of Uhambo was closely monitored throughout the trial, and participants were offered the local standard of care for preventing HIV, including access to oral pre-exposure prophylaxis (PrEP).

The DSMB examined data from 2,694 volunteers who received the investigational vaccine regimen and 2,689 volunteers who received the placebo injection, in an interim analysis on 23 January 2020. The analysis looked how many participants were diagnosed with HIV after at least 60% of the participants had been in the Uhambo study for more than 18 months, which is enough time for the vaccine to stimulate an immune response. In this analysis, 129 HIV infections occurred among the vaccine recipients, and 123 HIV infections occurred among the placebo recipients.

Based on these results, the DSMB concluded that the investigational vaccines had not shown any efficacy. The recommendations from the DSMB was to stop further vaccinations but keep participants in the study for follow-up.  Importantly, the DSMB did not suggest any concerns on the vaccine regimen’s safety. The report mentioned that there was no significant evidence of either decreased or increased infection rates with vaccination. “We remain deeply committed to the continued follow up of our participants and ensuring that they continue to explore ways of preventing HIV in their everyday lives” says Dr Fatima Laher, Protocol Co-Chair, from the Perinatal HIV Research Unit, in Soweto.

“The HIV pandemic is a threat to tackling the burden of disease in South Africa, finding an effective HIV vaccine is a journey,” says Dr Yogan Pillay, Director-General, National Department of Health. “We as a country, with the support of the global community, remain committed to the development of an effective vaccine,” concluded Dr Pillay.


HVTN 702/Uhambo is a study conducted by the Pox-Protein Public-Private Partnership (P5). The SAMRC is one of the international partners of the P5. Other partners include the Bill & Melinda Gates Foundation, the U.S National Institutes of Health, Sanofi Pasteur, GlaxoSmithKline, the HIV Vaccine Trials Network (HVTN), and the U.S Military HIV Research Program. The P5 was established to build on the success of the RV144 trial and to develop pox-protein HIV vaccines with the potential for broad public health impact through an extensive clinical and research programme.

Click here for the NIH press release and Q&As on the study

Release date: 
Monday, February 3, 2020 - 15:00
Dr Alfred Thutloa
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