Projecting the Demographic Impact of HIV/AIDS: Alternative Scenarios

Cheryl C. Sawyer, United Nations

In the 2002 Revision of World Population Prospects, the United Nations explicitly incorporated the impact of HIV/AIDS in 53 countries to the year 2050. The course of the epidemic was estimated and projected based on a four-parameter epidemiological model developed by UNAIDS. The parameters determining the future trajectory of the epidemic were assumed to remain constant until 2010, when behavioural changes and interventions would effect a gradual, sustained decline in HIV prevalence. We present the impact of AIDS on mortality and population structure as projected in the medium variant. We then look at the implications of several illustrative scenarios with alternative assumptions about various aspects of the HIV epidemic: a scenario in which the endemic rate of HIV prevalence remains high; a scenario in which the time from infection to death is extended; and a scenario in which an effective vaccine becomes universally available and prevents new infections.