Smoking affects health and immunity for years after stopping, studies show. adaptive immunity, built over time with infections, remains damaged for years.
Quitting cigarettes does not mean an immediate return to full health, say the researchers. Once you have stopped smoking, you have to wait ten years to regain a life expectancy comparable to someone who has not smoked at all, they say. The effect is notable regardless of the age at which you stop, even if it is more marked among those under 40.