[eynsham]

Studies like this suggest that there were Covid-19 infections in the US before they were first detected; they don’t suggest that they were terribly widespread. Unless flu is vastly less likely to cause these symptoms than Covid, or it turns out that the difference in prevalence was much smaller than, at least on current evidence of the trajectory of the pandemic, is plausible, ‘almost impossible’ looks to me like it’s rather understating the odds that it was flu/something else instead of Covid.