This theory of BCG vaccination and protection from COVID is intriguing. Is this a testable theory?
https://www.medrxiv.org/content/10.1101/2020.03.24.20042937v1.full.pdf">https://www.medrxiv.org/content/1...
https://www.medrxiv.org/content/10.1101/2020.03.24.20042937v1.full.pdf">https://www.medrxiv.org/content/1...
The study used mortality which seems like a fair way to get around that limitation.