Israeli study makes mainstream the already-known correlation between vitamin D and infection severity
14x risk of a severe infection if a person has deficient vitamin D level. According to another study from April 2020, risk of death from Covid 10x when the person has deficient vitamin D.
Yet not talked about by governments. Only vaccines.
Ivor Cummins comments that high vitamin D levels (or even adequate) is not just about taking lots of vitamin D pills, but rather is about eating an actually healthy diet of good foods, and also getting sun (up to a light pinkness not burning skin). But vitamin D pills are helpful in raising vitamin D levels, obviously.
Cummins says a comfortable level of vitamin D that makes for a decent immune system function is around at least 30ng/ml.
People used to have better vitamin D levels than now, according to Cummins. The percentage of vitaminD-deficient white people basically halved to 30% and black people went form like 10% to like 2% (melanin versus sun to produce vitamin D) between like 1991 and like 2002. Mexicans and other tawny people are in between whites and blacks.
D3 half-life (from vitamin D pills or from sun) is a day or two. Ie daily routine is important for vitamin D (you can't just superboost it one per week or something and expect results that will work every day in between these superboosts). When you eat the pills, it goes to your liver to be converted to the active metabolite 25-OHD. For a vitamin D-deficient person, they might need 5000 - 10,000 IU of the vitamin pills per day.