Every smoker knows the huge hit that you get when you light up the first cigarette of the day. The nicotine in the smoke reaches your brain in seconds and triggers what scientists call "reward receptors". Wow, you're hooked.
If you could stop nicotine getting to your brain - maybe, just maybe - you could undermine the physical basis of addiction to nicotine and avoid all the nasty things that tobacco smoke does to your body. That's the theory motivating a research group at Weill Cornell Medical College in New York.
They've genetically engineered mice so that they produce an antibody against nicotine - a bit like vaccinating against flu so your body produces antibodies against the flu virus.
The nicotine antibody floats around the mouse's bloodstream, gobbling up nicotine (like a molecular Pac-Man). That stops the nicotine getting to the brain and, hey presto, you're not addicted any more.
Well that's the theory. In fact, in their experiments, they only stopped 85% of the nicotine reaching the brain - 15% got through and no-one knows whether that's enough to quell the addictive response. And in their experiments the effect only lasts for minutes. And making antibodies in this way can go catastrophically wrong. And mice aren't humans.
In other words, this is a fascinating bit of science but still a million miles away from producing a "vaccine" that could help you stop smoking.
But suppose they can prove it works and that it's safe. Would it be ethical? If you vaccinate someone against flu, you change their bodies but in a way that protects them against a disease. If you vaccinated someone against nicotine, you'd change their bodies not to protect them against a disease but to protect them against a behaviour that led to disease. Would that be ethical?
You can read more about their research here.