Selenium appears to aid in upkeep with the immune system that can work to inhibit viruses but inhibit doesn’t stop them. We’re exposed to viruses everyday of some sorts. Virologist are finding more virus at random. They were surprise to find some large viruses as before they were assumed to be no bigger than a certain size which could be easier identified from germs. Corona is a large virus but not like the ones their finding although not deadly so far as I know.
Actually some virus aside from not being harmful to us, aid the host and in turn virus finds a home.
More funding should come their way. They have more understanding of things like polio than they did in the crude past for instance. They have different shapes and forms can capsules. Corona is lipid which makes washing with soap and water better than Alcohol because the soap breaks down the lipid.
Still the immune system has its fall backs. Persay if the cytokine action causes inflammation it can then depending where compromise the protective layers of a cell allowing a virus getting in. Sometimes that barrier can be between the cells of like the respiratory system and the bloodstream then goes systemic. Not to mention direct harm to cells in others.
More attention is needed in watching and disabling the immune system in a cytokine storm.
In this article it is limited in findings selenium preventing cancer though but in fact could contribute to skin cancer. FWIW selenium Depletes HIV virus
https://www.google.com/amp/s/abcnews.go.com/amp/Health/story%3fid=2813945&page=1