Vitamin D is needed in our immune system, and right now, our immune system is all we have to fight off Covid-19. It's also important for fighting off plain old flu, colds, and other invaders of our bodies.
It has become clear that people with darker skins, have been hit harder by Covid-19 than people with lighter skins. I've heard many opinions that this is for socio-economic reasons. Such as, a difference in job functions, a difference in quality of housing or a difference in access to healthcare (that would be in the USA).
But we also know that darker skins are slower to make vitamin D than lighter skins.
I like to think about evolution - we tend to acquire characteristics because they help us survive and flourish. It's generally accepted that Homo Sapiens came out of Africa, and were originally dark skinned. So why are so many people in temperate and cooler latitudes light skinned? The only advantage of a lighter skin, is that it's faster at making vitamin D, so the fact that people in the more northern latitudes have lighter skins, is surely because the synthesis of vitamin D is so important, it becomes a trait that is selected for by evolution.
Also, men are much harder hit by this virus than women, which is completely unfair, of course, and I'm starting a campaign to rectify this - equal rights for men! And as a non-young, somewhat burly, sunlight-averse male, I'm in one of the highest danger zones. I could only make it worse by taking up smoking.
I was tested several months ago, and the test showed that I was vitamin-D deficient. The test was fairly simple - they took a sample of my blood, and it was analysed in a laboratory. As a result, the doctor put me on a very heavy course of vitamin D tablets for three months, 70 micrograms per day.
When those pills ran out, I bought a tub of pills from the pharmacy, and took 25 micrograms per day; after a month or so, I got tested again, and that seemed to be keeping my D levels at a satisfactory level.
I've been following the Youtube videos of Dr John Campbell, and he's been asking why people aren't being tested for vitamin D deficiency, to discover if that is the reason for the difference in infection rates for darker skinned people. Maybe that isn't the reason, but it would be easy to check and rule it out. And if that is the reason, then it would be very easy to fix the situation - vitamin D pills are cheap and easy to get. He recommends 50 micrograms per day (that's 2000 International Units), and not to take more than 100. So I've ordered three tubs of them, enough for about nine months. I wanted to get Boots own brand (because I know they aren't fake), but they show as sold out, so I went to the Waitrose web site, found out what they sold, and ordered that brand from eBay. Because I know how easy it would be to make fake tablets and sell them online, so I want the real thing.