We take 4,000 iu of D3 daily as part of the Zelenko protocol. We haven’t had a sniffle since Nov 2022. I think that’s when we had covid which for us was a 3 day mild head cold and a lingering cough. We were never really sick. We never bothered to get tested.
If you are over 55 you should be on the Zelenko protocol. Our doctor can’t understand how we look, act and feel so much younger than our age.
I try to remember to take 1 pill of vitamin D (5000 IU) daily, and only because I get those free from my HMO doctor. Still in perfect health with no pains, no health issues at age 85. My thing is 23 minutes of brisk walk every day with 1 lb wrist weights. I will skip a meal before I skip daily exercise.