Thanks for reminding me, I just dumped some cinnamon powder into my coffee.
You're probably right though it looks like vitamin D should probably be the first line of defense.
Supplementation is a whole ‘nother world of possibility, with D3 right at the top of the heap as far as aiding viral resistance. Not so sure about bacteria, though. And cinnamon has useful qualities above and beyond smelling and tasting nice, as you point out.