New York Mayor Bill de Blasio is backing a plan that would see the city become the first in the U.S. to open supervised injection sites for intravenous drug users. The plan is aimed at ending an epidemic of overdoses—mostly from opioids—which saw more than 1,400 deaths in New York City last year alone. Cities in Canada and Europe say they’ve succeeded in cutting overdose deaths while combating HIV, hepatitis and other viruses by setting up safe injection programs.