This is a prospective open cohort study that will identify and prepare potential volunteers for future clinical research at KAVI-ICR while earning support from their communities and organizations. The target population in this program are individuals living in Nairobi and its environs. Up to 300 HIV negative participants will be enrolled. After reaching the upper limit of enrolment, those found to be HIV-infected will be replaced. Enrolment will thereafter continue to sustain this number whenever participants discontinue or are recruited into an observational study or a clinical trial. Enrolled volunteers will be followed up every six months for a period of about two years. No investigational product will be given.