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A major trial for a human immunodeficiency virus (HIV) vaccine across Uganda, Tanzania, and South Africa, known as PrEPVacc, has been stopped prematurely due to preliminary data indicating its ineffectiveness in preventing infections. The study, led by African researchers with support from European scientists, aimed to test two vaccine regimens on about 1,500 volunteers.
Despite existing drugs that reduce HIV risk and treatments to manage the virus, the vaccine’s failure dealt a blow to efforts in finding an effective preventive measure against a virus that has claimed around 40 million lives worldwide.
With over 39 million people living with HIV globally, and more than 25 million in sub-Saharan Africa, the quest for an effective vaccine remains critical, as highlighted by the Joint United Nations Programme on HIV/AIDS (UNAIDS) and the World Health Organization (WHO).
The trial, initiated in December 2020, ceased a year ahead of schedule following an interim review showing minimal or no impact in preventing HIV. Final findings are expected in late 2024.
Expressing regret over the vaccines’ inefficacy, Eugene Ruzagira, the trial director, conveyed the researchers’ determination to reassess strategies and better understand the challenge.
Funded by a £12.8 million grant from the European Union’s European and Developing Countries Clinical Trials Partnership, the research, besides testing experimental HIV vaccines, also evaluated a new form of oral pre-exposure prophylaxis (PrEP). This segment of the trial continues to explore the effectiveness of the new PrEP compared to existing versions.
Jonathan Weber from Imperial College London stressed the importance of transparency in clinical trials, acknowledging the need to ascertain if the vaccine regimens should be further developed or dismissed for HIV prevention.
Despite the setback, researchers remain resolute in their pursuit of an effective HIV vaccine. Pontiano Kaleebu, PrEPVacc’s chief investigator at UVRI, highlighted the need for a more region-specific approach to vaccine development.
While setbacks are inherent in vaccine development, the trial’s halt offers an opportunity for researchers to refine their understanding of HIV transmission and devise targeted interventions. The scientific community remains committed to overcoming challenges and advancing toward an effective HIV vaccine.
