HIV infection during limited versus combined HIV prevention programs for IDUs in New York City: the importance of transmission behaviors.

Objectives: As no single HIV prevention program has eliminated HIV transmission, there is growing interest in the effectiveness of "combined" prevention programming. To compare HIV infection among persons injecting in the initial programs environment (IPE) in New York City (self-initiated risk reduction, methadone, education/outreach, and HIV testing) to HIV infection among persons injecting in a combined programs environment (CPE) (above programs plus large-scale syringe exchange). To identify potential behavioral mechanisms through which combined programs are effective.