A key HIV vaccine trial has been cancelled after researchers found that it did not prevent the disease.
The news is a significant setback in the fight against the virus as the vaccine is the only one to have ever shown efficacy in an earlier trial led by the United States Military HIV Research Program and the Thai Ministry of Health.
“An HIV vaccine is essential to end the global pandemic, and we hoped this vaccine candidate would work. Regrettably, it does not,” said Anthony Fauci, director of the National Institute of Allergy and Infectious Disease in the US, which funded the study.
“Research continues on other approaches to a safe and effective HIV vaccine, which I still believe can be achieved.”
The HVTN 702 vaccine was being tested on more than 5,000 HIV negative volunteers aged between 18 and 35 at 14 sites across South Africa.
Half the volunteers received the vaccine while the other half received a placebo. But interim analysis, 18 months into the trial, showed that 129 people who received the vaccine became infected with HIV compared to 123 who caught the virus in the group that received the placebo.
Based on these findings the researchers decided that it was not worth continuing the study.
“The people of South Africa have made history by answering this important scientific question. Sadly, we wish the answer was different,” said Glenda Gray, chair of the trial and president of the South African Medical Research Council.
“We will continue to explore promising avenues for preventing HIV with other vaccines and tools, both in South Africa and around the world.”
Several other vaccine trials are ongoing but none are as far advanced as this one was. Experts insist that a vaccine is the only way to eradicate the virus, which killed 770,000 people in 2018.
Linda-Gail Bekker of the International Aids Society said: “Whilst this is a significant setback for the field, we need to continue the quest for a preventive vaccine. The rates of HIV infection, which continue unabated in this region, should spur greater urgency, global attention and investment to the quest.”