France had Covid-19 on November 16, hospital says after analysis of chest scans

They reviewed chest scans from November 1st, and came up with a first case on November 16th.

It begs a question - was the methodology good? Perhaps their method of review was flawed? False positives would explain the low consistent number of cases they found since November.

I think for this kinds of studies they should also do a blind analysis of a pre-covid month or two. Perhaps it would turn out Covid would be found in this data as well.

Does this call into question whether the virus arose in China? The last bit of news I saw from there said they had their first case on November 17.