The results of the PrEPVacc HIV vaccine trial conducted in Eastern and Southern Africa, which ran between 2020 and 2024, show conclusively that neither of the two experimental vaccine regimens tested reduced HIV infections among the study population. Vaccinations in the PrEPVacc trial were stopped in November 2023 (and publicly announced in December 2023) when it became clear to independent experts monitoring the study data that there was little or no chance of the vaccines demonstrating efficacy in preventing HIV acquisition. The PrEPVacc vaccine trial results, announced today at AIDS 2024 in Munich, Germany, report more infections in the two vaccine arms than in the placebo arms, but the researchers say they cannot draw a definitive conclusion about what this means because the statistical 'confidence intervals' for the comparison are so wide, indicating a high degree of uncertainty.
The researchers also highlight that the rate of HIV infection observed in the placebo group was unusually low and does not appear to be explained by a difference in the use of condoms or pre-exposure prophylaxis (PrEP). PrEPVacc is discussing with other groups worldwide further immunological analyses that could help to explain the differences in HIV infection rates between the vaccine and placebo groups. Across South Africa, Tanzania and Uganda, the countries where PrEPVacc has conducted its trial, UNAIDS estimates that in 2022, a total of 10.
7 million people were living with HIV and 244,000 adu.