It’s years in the future if it ever happens, and alcohol and marijuana present special problems that prevent them from being included even in the current research, but w0rk is continuing on efforts to create vaccines that prevent drugs like heroin or cocaine from having much, if any, effect on the user. Such a vaccine would not be a cure, but rather it would make the use of the particular drug vaccinated against have little or no effect on the user. So, for example, a user who wanted to be drug-free (that’s pretty much a prerequisite) would finish off a treatment program by getting a shot that would last for about six months. If he used, his immune system then would attack the drug molecules in his blood and destroy them.
You can read about the research in an article from the New York Times.
The research does raise the alluring possibility that at some time in the future, the day will come when addiction can be treated primarily as a medical problem.