I came across this review that was published in March and although it's somewhat outdated (research in this area has been going on for a couple of years now), I thought that it was incredibly interesting!
Apparently there are four drugs that lend themselves to immunotherapy: nicotine, cocaine, morphine/heroin, and methamphetamine. The authors of the review are proposing that vaccines be researched and developed to protect against addiction to these four drugs. The drugs themselves are too small of molecules to elicit an antibody response, but if they were conjugated to an immunogenic protein or a carrier they could elicit some kind of immune response. Research is already being conducted on anti-nicotine vaccines in rodents, and they have discovered nine potential carrier proteins. The theory behind the vaccines is that the antibodies could sequester the drugs and substantially reduce the amount of drug reaching the brain which in turn would reduce the amount of pleasure caused.
I'm sure that it will be a controversial topic (for example, when would be the appropriate age to vaccinate against drug addiction?) but you can't help but think of all the benefits that an "anti-drug addiction" vaccine could bring about. Tobacco abuse significantly increases the chance of contracting cardiovascular diseases and lung cancer. Injecting drug use helps facilitate the spread of numerous infectious diseases including HIV and hepatitis. If there were a vaccine, its impact would probably not be limited to only drug addiction and abuse. The indirect effects on the prevalence of lung cancer, HIV, and other diseases could be huge!
To read the complete review: http://www.nature.com.laneproxy.stanford.edu/icb/journal/vaop/ncurrent/abs/icb200917a.html