The researchers deducted that the herpes virus could have spread around the world much earlier than initially thought.
The team from the University of Barcelona who had been testing wastewater since mid-April for identifying potential new outbreaks also chose to run tests on older samples. It was nine months before the novel coronavirus was identified in China.
They first found the virus was present in Barcelona on 15 January 2020, 41 days before the first case was officially reported there.
The Quantitative Biosciences Institute (QBI) is a University of California organized research unit reporting through the UCSF School of Pharmacy. However, the surprising finding in March 2019 was only briefly stated at the end of the paper. They chose to check early in the day samples, taken between January 2018 and December 2019, and all proved negative "except for the one from March 12, 2019, in which the SARS-CoV-2 levels were very low but were clearly positive", the team said in a statement, utilising the official name of the herpes virus.
Spain has recorded more than 28,000 confirmed deaths and almost 250,000 cases of the virus so far. "Maybe it wasn't detected at the time because it was flu season and nobody was looking for it".
Last week, Italian researchers reported finding the virus on December 18 in Milan and Turin, two months before Covid-19 cases besieged northern Italy.
Spanish virologists found COVID-19 in Barcelona (pictured) waste water collected in March 2019. The DNA is then "amplified" in successive cycles until key bits of genetic material that are known to only exist in a particular virus are plentiful enough to be detected with a fluorescent probe.
Authorship and funding: This work was funded by grants from the National Institute of Mental Health and the National Institute of Allergy and Infectious Diseases, both part of the National Institutes of Health; the Defense Advanced Research Projects Agency; the Center for Research for Influenza Pathogenesis; the Centers of Excellence for Influenza Research and Surveillance of the National Institute of Allergy and Infectious Diseases; the Centers of Excellence for Integrative Biology of Emerging Infectious Diseases of the Agence Nationale de la Recherche (France); F. Hoffmann-LaRoche AG; Vir Biotechnology, Centre for Integrative Biological Signalling Studies (CIBSS), European Research Council (ERC) and the Ron Conway Family.
The University of Barcelona said in a press release on Friday that the study has been "sent to a high impact journal".
"When it's just one result, you always want more data, more studies, more samples to confirm it and rule out a laboratory error or a methodological problem", he mentioned.
Because of the virus's similarities to other respiratory infections, there was the potential for a false positive.
Professor Francois Balloux, director of University College London's Genetics Institute, who was not involved in the study, said on Twitter the research was interesting and the discovery of pre-existing T-cell immunity was "good news".
Bosch, who is president of the Spanish Virology Society, said early detection may have improved the response to the pandemic, even in January. The results indicated that the Barcelona group would repeat the experiments to confirm that it is really the SARS-CoV-2 virus.
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The very next day, China's state-run media Xinhua reported that a version of the law that could be voted on had been tabled. It is unclear if attending the rally would constitute a national security crime if the law came into force by Wednesday.
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However, both Pjanic and Arthur will remain at their current clubs for the remainder of the extended 2019-2020 season. Arthur joined Barcelona from Gremio in the summer of 2018 and enjoyed a solid maiden campaign at Camp Nou.