Same here, vit. D complex + vit. D3. April of 2019 I landed in hosp. with a bad flu and pneumonia. In retrospect, it had all the symptoms of COVID including loss of taste and smell, shortness of breath, high fever. I had to go on O2 for several days. I drove myself there but needed help to get from the car to the door. I nearly passed out and they had to send an orderly with a wheelchair. I was there for 10 days. At the time I lived in a building where nearly everyone was Chinese from China, recent immigrants who made frequent trips back and forth. I did take a COVID antibody test in May of this year, but it came up negative. So if I did have the virus, the immunity has faded by now. In hosp. they gave me a vit. D and B infusion since my levels were tanked out, also, potassium and magnesium. The infusion that I noticed almost immediate improvement was the vit. B. I’m continuing to take all three as oral supplements.