The Wall Street Journal reported that vitamin D supplementation may be helpful especially for people of color. (Ref: https://www.wsj.com/articles/vitamin-d-and-coronavirus-disparities-11587078141) My vitamin D level was chronically low and I was having repetitive sinus infections until I had it corrected. Higher doses of vitamin D (4000 iu / day) have been shown to potentially enhance the innate immune response to Denge virus replication. (Ref: https://pubmed.ncbi.nlm.nih.gov/31758375/?from_term=vitamin+d+immune+system+viruses&from_sort=date&from_pos=6)
There is no definitive data to show taking vitamin D supplements can help with Covid-19 yet to my knowledge. Theoretically, however, it makes sense and should be studied more. What do you think?