Frustrated by the high relapse rate of traditional addiction treatments, scientists worldwide were working on a strategy that recruits the body's own defenses to help addicts kick drug habits, The Wall Street Journal reported Tuesday.

The new approach uses injected vaccines to block some addictive substances from reaching the brain. If a vaccinated addict on the path to recovery slips and indulges in a drug, such as tobacco or cocaine, no pleasure will result.

Medications currently available to treat addictions typically work by mimicking a drug in the brain -- for example, methadone stands in for heroin and the nicotine patch for cigarettes. Other medications block activity in the brain's reward system. Alkermes' once-monthly Vivitrol injection does this for alcoholics and opioid addicts, while Pfizer's Chantix pills block the brain's pleasure receptors activated when people smoke.

Small molecule drugs like Chantix that function inside the brain can raise safety concerns. Chantix carries a federally-mandated warning to users of possible depression and suicidal thoughts. A spokesman for Pfizer noted that no causal link between Chantix and such symptoms was made.

By contrast, addiction treatment vaccines work in the bloodstream, not the brain. Clinical trials so far found no significant side effects, though the vaccines do nothing to combat cravings. They work by tricking the body to reject drugs as if they were foreign pathogens. Normally, tiny drug molecules wend their way through the bloodstream to the brain, unleashing a flood of chemicals involved with pleasure and gratification. The drug molecules are too small to goad the immune system into generating antibodies to fight them off.

Scientists figured out how to attach molecules similar to addictive drugs to much bigger antigens, such as deactivated versions of cholera or the common cold. When injected, these so-called conjugate vaccines spur the immune system to create antibodies to fight the tiny, addictive drug molecules. In several studies, these antibodies glommed on to molecules of nicotine, cocaine and heroin ingested by lab animals -- and in some cases, people -- and blocked them from triggering the brain's pleasure centers.

But it could be years, if ever, before any vaccines to treat addiction reach the market. Failures so far outnumber successes, and big pharmaceutical companies have not given their research muscle to vaccines for illegal drugs.

Click here to read more on this study from the Wall Street Journal.