Studies have shown that it was circulating in France back in November 2019. Not saying it originated there, there’s no indication of that, but there is a possibility that it had already been spreading for some time before December 2019.
“So far unpublished data, analysing retained wastewater samples from Barcelona, Spain, taken in March 2019 showed positive RT-qPCR results for SARS-CoV-2 (Chavarria-Miró et al., 2020). The authors conclude that the virus was introduced to the Barcelona population due to global travel and remained undetected.”
Yeah what I have seen about the Barcelona samples was not very convincing at the time, but then I am not an epidemiologist and I’d be happy to read more.
The French study has just been published last week [0]. It is based on a vast cohort study in which serum samples were collected regularly. They tested older samples and found some anti-SARS-CoV-2 antibodies. The article also mentions an Italian study with similar results [1].
https://academic.oup.com/cid/advance-article/doi/10.1093/cid...
Edit: removed incorrect conclusion