I had my vitamin D level checked yesterday as part of my six month PCR / CBC blood panel protocol. I am still waiting on my PCR results to see if I remain 'undetected' for bcr-abl without taking any dasatinib (20 mg). Fingers are crossed.
I posted my vitamin D test below to show how it is reported to me. I am at the level (70 ng/ml) I want to be () heading into flu season.
What is interesting is the reference range listed. It has changed. It used to show insufficiency below 20 now it is below 30. And the upper limit has been increased to 100 (use to be 80). As importance of vitamin D in immune health spreads within the medical community, I expect these number to change further. But you all here on this forum know the importance of vitamin D by now and to have it measured at least once per year if not twice and then to supplement to get it in range for maximum anti-cancer benefits let alone Covid prevention. I have zero concern or fear of Covid - or flu for that matter personally. I haven't had a cold, sore throat, cough, sinus, or flu of any kind in over 11 years - once I measured my vitamin D (17 ng/ml back then!) and did something about it. Twice I was exposed to Covid - (covid cough) - nothing. No antibodies detected either.
There are two major lymphoid immune cell groups which fight virus' in our immune system (and many lesser immune cell groups as well): antibodies (https://pubmed.ncbi.nlm.nih.gov/18651709/) -) produced by B-cells and T-cell's . Antibodies are the first line of defense. Antibody expansion triggers a massive T-cell response as needed to attack the virus and clear it before it can expand much. Vitamin D facilitates anti-flu T-cell expansion. Vitamin D also mediates T-cell reduction after the virus is gone so inflammation is reduced. Anti-inflammatory properties of vitamin D is little discussed. This property of vitamin D, T-cell moderation, is a key reason why even those who become sick with Covid are unlikely to experience cytokine storm (which is what kills in Covid). And with plenty of vitamin D and a healthy immune system overall, antibodies are likely to be produced in low numbers as T-cells expand to do their job and you never even know you were exposed. We are exposed to all kinds of germs and never know it. This is why.
Without sufficient vitamin D (> 55 ng/ml), your T-cells (and other cells too!) mobilize sluggishly leading to a much longer recovery.
It takes weeks and weeks to build up your vitamin D levels (and it takes weeks for it to lower as well). As the sun lowers in the sky (below 50 degrees) increase vitamin D intake beginning in fall and 'maybe' cut it back in the beginning of spring (but only if you plan on being out in the sun with minimal or no clothing). I take ~8000 IU' per day in winter and 5,000 IU per day in summer. And I take no vitamin D when I am scuba diving (which isn't often enough!) where the sun is high, the water is warm and tequila readily available. Testing is the only way to know your own personal vitamin D rhythm.