1. BACKGROUND 1.1 The HIV epidemic in Zimbabwe. The current situation of the HIV epidemic in Zimbabwe, and justification for HIV vaccines. Zimbabwe is reported to have one of the highest HIV/AIDS infection rates in the world. Data from national sentinel surveillance and national and local community based surveys show declining prevalence rates from 32% in 2000 to 22.1% (14.6%- 30.4%) in 2003 to 20.1% (13.3%-27.6%) in 2005 and now to 18.1% in 2006 in the 15-49 year age group. (WHO/UNAIDS 2006)1. Zimbabwe needs to sustain the declining HIV incidence and prevalence. There is enormous hope in the potential of an HIV vaccine to bring this epidemic under control. For decades, vaccines have proven to be among the most powerful and cost-effective disease prevention tool available e.g. the smallpox and measles vaccines. Vaccines also have a potential advantage of reaching populations that otherwise have limited access to health care and prevention services and they do not depend on consistent and sustained behaviour change by millions of individuals. In this third decade of the HIV pandemic, as the numbers of those infected by HIV and dying from AIDS remain dramatic, the need to find preventive and therapeutic vaccines that work is extremely urgent. 1.2 AIDS impact on development The AIDS epidemic has had a negative impact on life expectancy in the past three decades, particularly in Zimbabwe. Life expectancy at birth is currently 5