Well, I have been a smoker (off and on). I don't get flu shots. I don't get sick often, maybe once a year, with a cold or a stomach flu. Rarely bad enough to miss work, just work from home to keep my colleagues to from catching what I've got. Outside of that, my only real problem is an occasional kidney stone. I go for years without taking an antibiotic.

If it really is nicotine that does the work, a non-smoker could consider low doses of a nicotine replacement therapy, e.g. nicorette or it's copies from Walgreens, CVS, etc. I have used it for stopping smoking if I find it difficult and use the small lozenges.