National HIV Behavioral Surveillance (NHBS)
In 2003, CDC created NHBS for conducting behavioral surveillance among persons at high risk for HIV infection.
Process: Surveillance is conducted in rotating annual cycles in three different populations at high risk for HIV: men who have sex with men (MSM), injection drug users (IDUs), and heterosexuals at increased risk for HIV infection (HET). Before each NHBS cycle, formative research is conducted to learn more about the populations and collect data to help with sampling procedures. MSM are sampled using venue-based, time-space sampling methods. Health department staff members first identify venues frequented by MSM (e.g., bars, clubs, organizations, and street locations) and days and times when men frequent those venues. Venues (and specific day/time periods) for recruitment are chosen randomly each month. IDUs and heterosexuals are recruited using respondent-driven sampling, a type of chain referral sampling. Health department staff members select a small number of initial participants, or "seeds," who complete the survey and recruit their peers to participate. Recruitment and interviewing continue until the target sample size is reached.
Trained interviewers in all NHBS jurisdictions use a standardized anonymous questionnaire to collect information on HIV-related risk behaviors, HIV testing, and use of HIV prevention services. HIV testing is also offered to all participants. During each cycle, a minimum of 450 (for heterosexuals) to 500 (for MSM and IDUs) eligible persons from each participating jurisdiction are interviewed and tested for HIV infection. The first full round of NHBS, comprised all three cycles (MSM, IDU, and HET), was conducted during 2003–2007. The second round was conducted during 2008–2010, and the third round began in January 2011.
Which jurisdictions participate: As of 2011, 20 jurisdictions  with high AIDS prevalence are funded to conduct NHBS. Many of the health department grantees subcontract with local health departments, universities, or community-based organizations to implement NHBS activities.
What data are collected: Data on behavioral risks for HIV, HIV testing behaviors, access to and use of prevention services and HIV testing results are collected.
Findings from NHBS have been published in several issues of CDC's Morbidity and Mortality Weekly Report (MMWR)
How this surveillance contributes to HIV prevention: NHBS data are used to provide a behavioral context for trends seen in HIV surveillance data. They also describe populations at increased risk for HIV infection and thus provide an indication of the leading edge of the epidemic. Through systematic surveillance in groups at high risk for HIV infection, NHBS will be critical for monitoring the impact of the National HIV/AIDS Strategy, which focuses on decreasing HIV incidence, improving linkage to care, and reducing disparities.