My Dad was a paramedic. After his stroke, he came to live with me. He absolutely refused to have a flu shot. I started taking vitamin D3 supplements, and haven’t had the flu since I started that.
Which reminds me, I need to start taking them again, now that summer is over.
I agree. I posted this six years ago, started taking large doses of vitamin 'C' and haven't been sick since. (But I still get a flu shot)