The need to study HIV vaccines for both prevention and therapy remain paramount and urgent. The 2003 HIV estimates show that there 165000 infected children, 40000 new infections and 36000 deaths. Infant mortality rates have risen from 50 per 1000 live births in the early 1990s to 130 deaths per 1000 in 2003. This calls for studies using innovative interventions that show potential to turn around the epidemic and vaccine trials look most promising. A safe, effective and affordable vaccine that can both increase CD cell count and reduce viral load will show great therapeutic impact and improve survival particularly in resource poor countries. Ref J Stover et al. The epidemiological impact of an HIV/AIDS vaccine in developing countries. Sponsored by the European Commission and World Bank. 2. CHALLENGES INVOLVED IN DEVELOPING AN HIV VACCINE The development of a safe and effective vaccine against HIV infection involves several challenges. The ideal vaccine should stimulate immunological responses capable of blocking the sexual, injecting and vertical transmission of HIV infection. It must also be able to produce not only antibodies capable of neutralizing free viral particles but also immunological cell responses able to destroy HIV infected cells. There is the additional challenge involved in our not knowing the correlates of immunity to enable us to define what to expect from an effective vaccine. In addition, 10