As I type this during a rainy day, Ivor's video is an extremely balanced way of addressing the role of vitamin D and and identified resistance to contracting viruses. Given the information, I suggest it's far better for people to supplement with D3 than the alternative. Even before getting the recommended 25-Hydroxy Vitamin D test, it's a good idea to supplement, especially if you live in an area where it's difficult to get out in the sun frequently and/or you are older. Coupled with other metabolic health deficiencies, having a low level of vitamin D appears very risky. I'm taking 5,000 IUs when I'm able to get out in the sun and 10,000 when I'm not. Better safe than . . . . . . .

For those concerned with taking too much D, here's an excellent video by Dr. Mahtani:

https://www.youtube.com/watch?v=VQkx06k7AKk