[Randomization of a population for a clinical trial of immunization against the human immunodeficiency virus (HIV)].

Serum HIV antibodies has been investigated in different subpopulation from four different regions in Zäire by Elisa (Elavia Pasteur) and Western Blot. Seropositive prevalence differed from 2.4% (rural population) to 12.5% (urban population) according to the regions. When the group with 2.4% migrated to the area with 12.5% positives, after 8-12 months the number of seropositives in this group raised to 8%, showing an increase of 5.6% within one year. Such population is suitable for a large scale clinical trial (with anti-AIDS vaccine) to be performed on individuals with high risk of natural infection.