My wife and I (both in our 70s) spent 18 months doing volunteer service in a foreign country. We noticed that many people we worked with were often sick with colds, flu, and Covid. Speaking with some "natural healers" in the country, they said that the population is often sick, due to depleted soils, use of pesticides and herbicides on farmed produce, and poor water quality. Also there is an almost total lack of organic food. I was sick a total of once, for perhaps 2 days, and my wife was sick twice for maybe a week. We both religiously took Not Sick twice daily, and we believe that accounts for our ability to avoid getting ill, while others around us seemed much less healthy.