I read it in Nicholas Wade's article: https://nicholaswade.medium.com/origin-of-covid-following-the-clues-6f03564c038 https://nicholaswade.medium.com/origin-of-

I read it in Nicholas Wade's article: https://nicholaswade.medium.com/origin-of-covid-following-the-clues-6f03564c038 https://nicholaswade.medium.com/origin-of-covid-following-th... (long read). Some more reading: https://www.news-medical.net/news/20210217/The-origin-of-SARS-CoV-2-furin-cleavage-site-remains-a-mystery.aspx https://www.news-medical.net/news/20210217/The-origin-of-SAR... All these lines of evidence and reasoning show that the acquisition of the polybasic furin cleavage site by SARS-CoV-2 is a “missing link” in our understanding of its evolutionary history, that can only be addressed through the discovery of new viruses.”