I think @White_Wolf is talking about a study [0] done in 2020 by the university of Barcelona. But at the time the study was still in peer review phase.

The discovery of virus genome presence so early in Spain, if confirmed, would imply the disease may have appeared much earlier than the scientific community thought.

There was the potential for a false positive due to the virus’ similarities with other respiratory infections.

The research has been submitted for a peer review.

[0]: https://www.reuters.com/article/us-health-coronavirus-spain-...