I could believe that some people have a natural immunity to nicotine, because my late father & I both appear(ed) to have it. And that it may be possible to induce that immunity in others, by something like a vaccine.
Shortly after I enlisted in the Army I tried to take up smoking, age 20. Smoking in the Army was all around me in 1969, everyone did it, there were even cigarettes issued to us in our C-ration boxes. I was very much a conformist in those days, didn't want to be the odd-man-out who didn't smoke.
But after nearly a year of trying I still found it unpleasant, and never did get hooked. I considered it an expensive chore to smoke (even at Army tax-free prices, but then I made so little), and so I simply stopped. And there were no withdrawals, no change in me at all, no effort or difficulty whatsoever.
And my Father had been the same way when he stopped cold-turkey in the late 1950s, too. He'd smoked because of peer pressure like me, as he told me himself, and simple habit, a cigarette being a kind of man's fashion accessory back then. But he read about cancer and other health warnings, already being sounded that long ago, so he decided to quit, and did overnight. My Mother, on the other hand, was seriously addicted, and never could quit, even with my Father and doctors trying to help her.
So I can believe there is some component, genetic or whatever, that allows certain people to resist nicotine addiction. And I hope research shows a way to create that same immunity in everyone who wishes to quit smoking.