here's an interesting article about rats, heroin and a heroin
"vaccine."
near the end of the article: "The most intriguing test, however, involved rats that had been allowed to self-dose with heroin, which was accompanied by a blinking light. After an extended withdrawal, the rats would go right back to self-medicating if they were given a single dose of heroin or shown the blinking light. Once they were treated to raise the dynamic antibodies, however, the dose of heroin would no longer set off a bout of drug-taking (though the blinking light still would). The antibodies appeared to block the drug efficiently enough that it no longer registered in the brains of these rats."
so the rats don't need the hit of heroin to set off a binge. just blinking the light at them does that. so for humans, with our much more complex brains and emotions, consider that life itself it the blinking light. your triggers are the blinking light. even with the vaccine, as long as you're exposed to the blinking light the cravings will still kick in. you might not go on a binge but you'll still have the same cravings and take the hit even though it doesn't effect you. worse, since you're not feeling the effects, it's possible that you take larger and larger hits. last paragraph: "Vaccinating the rats required three doses within a month, and the rats still could get a hit off the drug—it just took a lot more of it." interesting stuff.