Faith Nyasuguta
The PrEPVacc study, conducting the first trial in Africa for two combination HIV vaccines, has been halted after researchers determined their ineffectiveness.
The trial involved 1,500 participants aged 18 to 40 in Uganda, Tanzania, and South Africa, testing two different combinations of HIV vaccines.
Initiated in December 2020, the African-led trial ceased last month following an interim review of its progress, with the final results anticipated to be disclosed in late 2024.
The vaccines, part of the Pre-Exposure Prophylaxis (PrEPVacc) trials, aimed to assess their efficacy in preventing HIV infection in populations particularly at risk.
Led by African researchers and supported by European scientists, the trials received a €15 million (£12.8 million) grant from the EU’s European & Developing Countries Clinical Trials Partnership.
Dr. Eugene Ruzagira, the trial director from the Uganda Virus Research Institute (UVRI) and an assistant professor of epidemiology at the London School of Hygiene & Tropical Medicine, conveyed that the independent data-monitoring committee’s analysis led to the conclusion that there is little or no chance of demonstrating the vaccines’ effectiveness in reducing the risk of acquiring HIV.
Vaccinations for PrEPVacc trial participants have been halted based on this assessment.
While the vaccine trial is discontinued, the trial of a pre-exposure prophylaxis (PrEP) pill, running concurrently with the vaccine tests, will continue. PrEP involves administering antiretroviral drugs to individuals at high risk of HIV to prevent infection.
Prof Jonathan Weber from Imperial College London, one of the trial’s sponsors, emphasized the importance of clinical trials in exploring unanswered questions. He stated, “While we await the final results and analysis of individual products, I believe that our interim result puts this generation of putative HIV vaccines to bed.”
The decision to halt the trial mirrors a similar circumstance in South Africa, where a trial testing the only vaccine showing some success against HIV – the RV144, developed in Thailand – was stopped in February 2020 after interim results indicated its ineffectiveness.
Prof Pontiano Kaleebu, PrEPVacc’s chief investigator at UVRI, acknowledged the significance of developing an effective vaccine to prevent HIV infection, especially in Africa. He noted the urgency of this goal as there are currently no HIV vaccines being trialed for efficacy worldwide.
Despite the challenges, Dr. Ruzagira expressed optimism for the future, stating at an AIDS conference in Zimbabwe, “The scientific hurdles are high, but I have equally high hopes that an HIV vaccine will be developed one day.”
With approximately 39 million people globally and more than 25 million in sub-Saharan Africa living with HIV, the need for effective prevention measures remains a critical public health priority.
The PrEPVacc trial’s halt highlights the complex nature of HIV vaccine development, emphasizing the ongoing pursuit of innovative approaches to combat the global HIV epidemic.
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