Doc does vitamin D level tests along with all the others on a regular basis. Back before COVID I came up a bit low and started supplements, later I increased to 6000 units per day (about 7 times RDA), no issues. The stuff is cheap insurance against a lot of things besides COVID.

'Four legs good, two legs baaaad."
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"Jimmy, some of it's magic,
Some of it's tragic,
But I had a good life all the way."
(Jimmy Buffett)

SotG