3. GOALS OF AN AIDS VACCINE Primarily, the goal of vaccines is to prime the immune system to recognize and protect against a disease caused by a virus or other infectious agent. To have a significant public health impact on the AIDS pandemic a vaccine must be both effective against the wide diversity of global HIV isolates and useful in the developing world, where the need is greatest. The second potential goal is to significantly suppress viral load and slow the progression to AIDS in vaccines if they become infected by HIV. It is important to note that while developing an AIDS vaccine that meets the goals outlined above is a scientific challenge, the resources required to do so—funding, technical, and human resources—will only be available if political will supports it. An enabling political environment is necessary to provide the mobilization of resources required to conquer this pandemic. 4. VACCINE EVALUATION PROCESS Before an HIV vaccine candidate product is evaluated in human subjects, trials to determine the vaccine safety, toxicity and immunogenicity are conducted in small animals and later in non-human primates. After these pre-clinical phases, and if the vaccine products are safe and capable of stimulating the immunological system, they can enter the human phase of clinical trials. Phase I and Phase II trials of safety and immunogenicity of vaccine candidate products are usually conducted in approximately 40 to 200 human volunteers, and the effectiveness in human subjects is determined in Phase III studies, randomized and with appropriate controls, carried 13