Letter to world governments signed by over 100 scientists and doctors recommending vitamin D supplementation of at least 4,000 IU per day: https://vitamindforall.org/letter.html   Study: 80% of COVID-19 patients are vitamin D deficient: https://www.ajc.com/.../study.../A6W5TCSNIBBLNNUMVVG4XBPTGQ/   Study: Vitamin D3 supplementation nearly doubles survival rate in nursing home patients: https://www.sciencedirect.com/.../pii/S096007602030296X   Vitamin D is the #1 anti-cancer vitamin: https://www.chrisbeatcancer.com/vitamin-d-the-1-anti-cancer-vitamin/   Minimum 4,000 IU is recommended per day. Start with 10,000 IU per day for 2-3 weeks if you haven't been taking D3 or if you are in the high risk SODA group: Seniors, Obese, African descent or dark skin, Diabetic.   I personally take 10,000 IU per day in the winter. 5,000 IU with breakfast, 5,000 IU with dinner.