One of the key challenges in HIV vaccine development has been finding a way to train the immune system to produce antibodies that can target many variants of the virus.

Traditional approaches have not worked, largely because HIV mutates rapidly and hides key parts of itself from the immune system.

Now, a new study combining data from two separate phase 1 clinical trials shows that a targeted vaccine strategy can successfully activate early immune responses relevant to HIV, and, in one trial, further advance them – a key step toward a long-sought goal in vaccine development.

Conducted by an international team led by scientists at IAVI and Scripps Research, the trials included nearly 80 participants from both North America and Africa, laying essential groundwork for a future HIV vaccine with global potential. The study, which involved Kenyan researchers, was published in Science on May 15, 2025.

One of the trials tested a stepwise vaccination strategy, in which a priming dose and a distinct booster dose were given sequentially to guide the immune system through stages of antibody development.

That trial demonstrated that administering this combination – a technique known as heterologous boosting – could further advance the immune response in humans. The second trial focused on the priming stage and showed that an initial vaccine dose could successfully activate the desired immune cells in African participants, supporting the use of this approach in regions most affected by HIV.

Source: The Star Newspaper