In AIDS vaccine trials the vaccine candidates need to tested in the populations at greatest risk of becoming infected with HIV. This allows researchers to be sure that the vaccine is safe and effective in these individuals. The high risk groups vary. Some people may be considered at high risk of contracting HIV just by living in a certain place or community. Others are placed at risk of HIV infection by their personal behaviors or occupations, for example injection-drug users. The ethics of clinical trials in high risk groups require that all the high risk individuals are given some guidance on reducing their personal HIV risk. Recruiting high risk individuals can be challenging, such groups may be stigmatised or hard to reach.
IAVI. Understanding The Recruitment Of Volunteers At Risk Of HIV Infection - May 2008. Why Are Volunteers Who Are At High Risk Of HIV Infection Necessary Participants In Late-Stage AIDS Vaccine Trials? (2008)