CNN Chief Medical Correspondent Dr. Sanjay Gupta

In a 3-part series titled PRIMARY CONCERN: HEROIN – to debut on Anderson Cooper 360 – CNN Chief Medical Correspondent Dr. Sanjay Gupta examines the heroin epidemic that has become a nationwide crisis and potent political issue. Dr. Sanjay Gupta joined John to talk about the special, and how heroin use became such a big problem that it came up at the latest Presidential debate.