The mover– stayer model for the HIV/AIDS epidemic in action

Short- and medium-term projections of the HIV/AIDS epidemic indicators are of great interest to those evaluating the needs for health care and prevention interventions. We developed a simulation procedure to obtain forecasts of the HIV/AIDS epidemic and used it to estimate the characteristic regional parameters of the epidemic in Italy. The simulation procedure is based on a hybrid compartmental model, in which the epidemic evolves via nonrandom mixing patterns. Because of its structure, the model is suitable for policy making; in particular, for evaluating prevention campaigns, alternate forms of health care for people with AIDS, and drug supply needs. The model will also be used to estimate the number of intravenous drug users in Italy and the number of AIDS cases not reported or reported with a delay to the Italian surveillance system.