Prevention of HIV/AIDS with vaccines:

HIV vaccines are urgently needed to help control the relentlessly expanding epidemic. However, the development of a safe and effective vaccine for this rapidly mutating virus which produces life-long infection is elusive. Feasibility of HIV vaccination has been demonstrated by challenge studies in primates and by the presence of neutralizing antibodies which confer passive protection and can be detected in vitro. Given safety considerations, the first vaccines developed have been recombinant subunit vaccines consisting of viral envelope antigens formulated with adjuvants or incorporated into live vectors, such as vaccinia and avipox. Subunit envelope vaccines have proven to be safe and immunogenic in human phase I trials. Two gp120 subunit products are being considered for phase III trials based on ongoing evaluation of data from a phase II trial, primate-challenge studies, and laboratory studies evaluating the breadth, magnitude, and duration of immunogenic responses, including neutralization against recent isolates. Efficacy trials will be large and complex, involving people at high behavioral risk for infection. Baseline studies with recruitment goals of over 10 000 people are being sponsored in the USA, with many additional vaccine preparedness studies being sponsored in developing nations by international and national authorities. Because high-risk populations will be recruited for trials of many year's duration, new approaches to trial design and community participation will be needed in order for these trials to succeed. Systems must be in place,to ensure that trial participants receive preventive counseling and services to minimize discrimination from vaccine-related seroconversions. Here we document the urgent need for HIV vaccines, provide a brief preclinical and clinical update, and present the plans and considerations for testing HIV vaccine efficacy.