Last year, on the eve of World International Aids Day, the scientific community embarked on a large-scale clinical trial of an HIV vaccine. This was after an experimental HIV vaccine regimen was tested in a small clinical trial. It was given a thumbs-up, in what's believed could lead to the first licensed vaccine against the virus that causes AIDS. The large-scale trial involve 5,400 HIV-negative men and women in South Africa, testing for efficacy, or whether the vaccine actually protects those who receive it from becoming infected with HIV. Sakina Kamwendo speaks to Dr. Carl Dieffenbach, Director of the Division of AIDS, U.S. National Institutes of Health, Ntando Yola, Community Engagement Coordinator at the Desmond Tutu HIV Foundation and Dr. Susan Buchbinder, Researcher from the University of California, San Francisco to unpack the issue.