Abstract
Due to stigma or legal issues, populations with higher HIV risk are often hard to reach, which impedes accurate population estimation of HIV burden. To better sample hard-to-reach populations (HTRPs) for HIV surveillance, various sampling methods have been designed and/or used since HIV epidemic following the first reported AIDS cases in 1981. This paper describes the development and the assessment (i.e., validity and reproducibility) of approximately eight sampling methods (e.g., convenience sampling, snowball sampling, time location sampling, and respondent-driven sampling) for HTRPs in HIV surveillance, with a focus on respondent-driven sampling (RDS). Compared to other methods, RDS has been greatly assessed. However, current evidence is still inadequate for RDS to be considered the best option for sampling HTRPs. The field must continue to assess RDS and to develop new sampling approaches or modifications to existing approaches.