The two rounds of IBBA were conducted in 29 districts from six high prevalence states including eight districts
in Andhra Pradesh, five districts in Karnataka, six districts in Maharashtra, five districts in Tamil Nadu, two districts in Manipur and three
districts in Nagaland. The target sample size was 400 per group, per district for FSW and their clients, high-risk MSM, IDU, and 500 per route
category for truckers. In case of transgender in Tamil Nadu, a sample of 400 was selected from five districts combined. Overall, a total of 27,638
respondents were covered in R1 and 24,459 respondents in R2. Conventional cluster sampling, time-location sampling and respondent driven sampling were
the methods used for selection of respondents.
Ethical clearance for the assessment was obtained from the ethical committees of participating ICMR institutes and from FHI 360ís Protection of Human Subjects Committee (PHSC). Informed consent was taken from the respondents before the administration of questionnaire and sample for biological tests and protection of confidentiality of respondents was given high priority. Intensive training was imparted to all field personnel associated with IBBA. Behavioural data was collected using a structured questionnaire. Blood and urine samples were collected by trained clinical staff and tested to estimate the prevalence of HIV and STIs.