I too have used and preached the use of Vit C and Zinc for fighting and avoiding flu and soar throats (for 3.5 decades in my case) And no I am not peer reviewed on those opinions LOL.
We have some things in common
" I have avoided the flu for decades by using Echinacea, C, and Zinc at the first sign of a sore throat or any thing that made me believe a cold or flu could be coming on. One must realize with Echinacea that it should only be taken for a week or two and then stopped for a couple weeks to be effective. Taking it constantly is useless. "
I am only just starting to read up this month on Echinacea. Thanks for that Info!
I assume you are using Vit D-3 as well now?
I take 9000 IU / day of D-3, the amount recommended by my RA MD