A research team from the University of Barcelona, one of Spain's most prestigious universities, said Friday that they had detected traces of coronavirus in wastewater samples collected on March 12, 2019, nine months before COVID-19 was identified in China.

The research has been submitted for peer review, and researchers say more testing is needed to support the findings. 

"These results, sent to a high impact journal and published in the archive medRxiv, suggest the infection was present before knowing about any case of COVID-19 in any part of the world," the statement said. "Those infected could have been diagnosed with flu in primary care by mistake, contributing to the community transmission before the public health authorities took measures."

The study was led by researchers from the Enteric Virus Laboratory of the University of Barcelona in collaboration with the public-private company Aigues de Barcelona, which is responsible for managing the water cycle in Barcelona's metropolitan area.