Dr. John Campbell suggests Vitamin D may lower complications from coronavirus. My Dr. prescribed 7000 IU long before this pandemic. Be safe and take some, unless you get lots of sunshine daily. Dark skin produces less than light colored skin per hour of sunlight.
Why single out individual essential substances? All vitamins are crucial. Only if your diet is deficient in something should one support the multi-billion dollar businesses peddling as many pills as yhey can. If sunshine is low, and your diet is poor in vitamin A, I can see a logic in taking pills to boost the level, but .....
Just ensure you have a proper diet, and keep fit.
Apparently people who work inside a lot might not have enough D. But only blood testing can give exact amounts and then that could fluctuate.