Today, 19 HIV candidate vaccines

Today, 19 HIV candidate vaccines are at different levels of clinical testing in Europe, the United States and elsewhere. The first large-scale Phase III human trials of HIV vaccines are under way in the United States and Thailand. These involve 5400 volunteers in the United States, with sites in Canada and the Netherlands, and 2500 volunteers in Thailand. The trials involve the use of candidate vaccines based on gp120 (the envelope protein of HIV) corresponding to the virus types most commonly found in Europe and North America (B) and Thailand (E). Definitive results from the North American trial are xpected to be available at the beginning of 2003, with results from the Thai trial a year later. While these initial trials may not result in the ideal vaccine, they may help advance the science and provide valuable information for future research efforts.

The next Phase III trial, using a prime-boost combination – a anarypox-HIV recombinant vector followed by gp120 – is due to start in Thailand at the end of 2002 or beginning of 2003. Other novel candidate vaccines are being developed in the laboratory and undergoing initial Phase I/II human trials and it is expected that the best products will move to additional Phase III trials in the next 3-4 years.

In the meantime, WHO and UNAIDS are working to facilitate trials in African countries through the African AIDS Vaccine Programme (AAVP), an initiative adopted in 2001 by African Heads of State at the African Summit on HIV/AIDS, Tuberculosis and Malaria in Abuja, Nigeria. The AAVP has launched an appeal for US$ 233 million for the next seven years, to help accelerate the development and testing of a vaccine for use in Africa. Some of the funds will be used to strengthen the capacity of African research centres to conduct clinical trials of vaccine candidates.