An experimental HIV vaccine was safe and triggered strong immune responses in healthy adults and monkeys, the researchers report. They say it also protected two thirds of the monkeys against a virus similar to HIV. Although the results of animal studies are not always the same in humans, the researchers are encouraged by this early-stage study, which included nearly 400 healthy people. For their next step, they are launching a new vaccine trial that will include 2,600 women in southern Africa who are at risk of HIV infection. The experimental vaccine against HIV-1 is one of five that have progressed to the effectiveness tests in humans. Although previous experimental vaccines against HIV-1 have generally been limited to specific regions of the world, this vaccine combines different HIV viruses. The goal is to unleash immune responses against a wide variety of strains of HIV, according to the authors of the study published Friday in the medical journal The Lancet. Around 37 million people worldwide have HIV / AIDS, and there are 1.8 million new cases a year.