A Black Swan development that shows that the COVID-19 virus is not the cause, or not the only cause, of COVID-19?
From The Guardian: "Many of the children having treatment for the new syndrome have tested positive for coronavirus, but others have not. That could mean that the syndrome is not related to coronavirus, that the children had cleared the virus before they were tested, or that the test missed the infection."
https://www.theguardian.com/society/2020/apr/29/more-cases-of-rare-syndrome-in-children-reported-globally