I haven't bothered with a flu shot in over 8 years. I take 10,000 IU Vitamin D3 for my immune system, and that TOTALLY protects me from sore throat, colds, chest colds & flu. Ditto for the wife.
For decades, I suffered with TERRIBLE chest colds every winter. Also the flu every time it came around. It used to be so bad that I was afraid to go outside or go to church!
Not any more. Vitamin D3 Geltabs totally protects me.