Every September - March I would feed the family Zinc and Vitamin C (over the counter stuff like this one) I use to get massive head colds that would go down into my chest and it would be a month of misery. Wen I did this combo from September through March all my colds went away. I no longer get a cold and I only take one capsule daily of both. I also don't get the flu but that is a natural immunity. I don't take the shot for flu either because when I did I ended up ill for 6 weeks so never made that mistake again. So now no colds, no flu...however since Covid is a illness enhancer I wear a mask in public. So no colds, no flus, and so far no Covid