2. Therapeutic vaccines or active immunotherapy: to prevent or delay the progression of the disease, to decrease the viral load in HIV-infected individuals and to decrease the transmission of HIV infection from infected individuals to their contacts; 3. Perinatal vaccines: to prevent the progression of the disease in HIV-infected pregnant women and the transmission of the viral infection to their children. There is a growing optimism in the international scientific community concerning the possibility of developing safe and effective preventive vaccines. However, despite the progress in recent years, the correlates of immunity associated with protection are still not well established hence the need for further research. Viruses isolated from different patients, and specially from different geographic regions, show considerable genetic and thus antigenic variations, which may be a limiting factor to the development of a universal vaccine hence the need for country level involvement in HIV research. It is important to know whether the HIV-1 strains circulating in the country where the vaccine might be used in the future are sufficiently related to the vaccine prototype being tested. In order to obtain this type of information, it is necessary to keep an HIV molecular surveillance program in the country, systematically collecting blood samples for HIV isolation and its biological, genetic and antigenic characterization. Results on HIV vaccine to date are encouraging, the trials of immunotherapy or post infection immunization need to be expanded and deepened in order to allow a better assessment not only of the immunological response but also of the clinical and virological parameters, including the effect on HIV transmission, development of AIDS and time of survival. 12