Spanish virologists have found traces of the new coronavirus in Barcelona wastewater samples collected in March 2019, the University of Barcelona said on Friday, reports Reuters in a dispatch.
However, caution should be exercised, as this study has not yet been published in any scientific journal. But if the presence of the virus in March 2019 is confirmed, it would prove that the Covid-19 was already circulating nine months before its first declared appearance in China.
In Italy, the Higher Institute of Health (ISS) had also detected traces of Covid-19 in the wastewater of Milan and Turin before the census of the first patient in the country. But with a less spectacular time difference: traces of viruses were identified in December 209, two months before the first reported case.
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The team at the University of Barcelona behind this discovery had already observed traces of the coronavirus genome in the city’s wastewater from January 15, 2020. Or 41 days before the very first official case in the capital from Catalonia.
A risk of false positive
After these encouraging results, the researchers decided to analyze older samples. Traces of the virus were thus discovered in samples dated March 12, 2019. “SARS-CoV-2 levels were low but positive,” said research manager Albert Bosch, quoted in the university.
But it is still too early to draw definitive conclusions. “When you only have one result, you have to wait for more data, more studies, more samples before you can confirm it and definitively exclude a laboratory error or a methodological problem”, a cropped Dr. Joan Ramon Villabi, of the Spanish Society of Virology, approached by Reuters. The scientist thus evokes significant risks of false positive, because of the similarities between the coronavirus and other respiratory affections.
