I've literally tried everything to prevent cold or flu. Vitamin D at the right dosage amazingly works. So many people reported that it actually works compared to anything they tried. If Pauling had moved up a letter to D, he'd win another Nobel Price because vitamin D at the right dosage would have tremendously effect on our health in the long run. Thanks to idiots for sun scare, we now have a widespread vitamin D deficiency that probably is the main reason why we have so many vaccines.