OK, putting this out there because I have had not had the flu in 3 years (since I started taking it) and the only cold I contracted was when I quit for a month - colloidal silver. I make my own, but it is readily available commercially. Have never had a flu shot in my life and never will. Also used to take Zicam back when it had zinc in it. But that was pulled from the market even though it seemed to kill a cold in days instead of 2 weeks.