A vaccine for addiction to cocaine and other stimulant drugs is on the horizon, writes psychiatrist and former White House antidrug official Keith Humphreys in the Wall Street Journal. The idea of using the body's immune system to combat the effects of addictive drugs goes back to animal studies conducted in the early 1970s, but the first evidence that a vaccine could help people with cocaine addiction didn't emerge until 2009. A vaccine would mean that a cocaine addict's body would treat the drug like an invading germ and produce antibodies that bind to it and change its size and shape.

The cocaine the addict ingested, which once would have crossed into her brain rapidly and en masse, would get there slowly, if at all. In colloquial terms, cocaine would be no fun for her anymore. A vaccine would not be a magic bullet; it couldn't stand on its own as a solution to cocaine and methamphetamine addiction. Cognitive-behavioral psychotherapy and 12-step groups have been shown to reduce stimulant drug use in rigorous research studies. Another approach using small, prompt rewards contingent on stopping drug use—rewards like meal vouchers and movie tickets—has been shown to be effective both in health-care settings and in the criminal justice system.