Please do keep in mind the time it takes to gather the data needed and then to write, peer review, and publish a rigorous epidemiological study.
You'd be very hard pressed to meet that standard in less than 9 months. Which means the first solid epidemiological evidence would not be available until, if we say that the epidemic went global in Feb 2020, until Nov 2020. And guess what, there it is!
https://www.healthaffairs.org/doi/10.1377/hlthaff.2020.00818
Please do keep in mind the time it takes to gather the data needed and then to write, peer review, and publish a rigorous epidemiological study.
You'd be very hard pressed to meet that standard in less than 9 months. Which means the first solid epidemiological evidence would not be available until, if we say that the epidemic went global in Feb 2020, until Nov 2020. And guess what, there it is!