At the onset of the study, three seeds were chosen to begin the recruitment chain for each population. Seeds were chosen according to their social status and connection to the MSM and FSW communities, ability to explain the purpose of the study and requirements of participation to others, enthusiasm about the study aims, and willingness to promote the project. The research team also aimed to select seeds representing diverse demographics (age, education, socioeconomic status), risk status, sexual practices, and sub-group membership.