Maybe its all that green tea they drink. Supposed to be good for you. I dont know.
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Your comment prompted me to check since I take EGCg(green tea component) twice per day for immunity/anti-cancer( https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2363808/ ) purposes. Seems it DOES have anti-viral properties also. Good to know and thanks!
Search words: egcg coronavirus pubmed
Results: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5759362/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6222519/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6152177/
So, if it's good for the outside, it must be good for the inside. I may just start drinking the stuff myself.