A computer model has created the most effective formula for reducing the spread of HIV among drug users in New York City over the next 25 years. Developed by researchers at Columbia University’s Mailman School of Public Health and Brown University, the model recommends a combination of interventions, including increased HIV testing, improved access to substance abuse treatment, increased use of needle and syringe exchange programs, and broad implementation of antiretroviral treatment as prevention. The result would lower new infections by more than 60 percent by 2040. Results are published online in the March issue of Health Affairs.