The study, published by researchers at the University of Barcelona, is in the preliminary stages and requires further verification.
CORONAVIRUS – The conclusions are to be taken with tweezers but the question. Spanish scientists at the University of Barcelona have announced they found traces of new coronavirus in a sample of the city’s wastewater from March 2019, more than a year ago. In the Catalan capital, the first traces of Covid-19 date back to January 2020.
To make these discoveries, the researchers analyzed wastewater samples over a period from January 2018 to December 2019, by performing PCR tests. “SARS-CoV-2 levels were low but positive,” said research manager Albert Bosch, also president of the Spanish Society of Virology.
“Barcelona is an important center for commerce and business. The city usually hosts massive events that attract visitors from around the world. However, it is likely that similar situations have occurred in other parts of the world and that they have had cases of Covid-19 that went unnoticed, ”write the study authors.
Their work is currently in the pre-publication stage and requires further independent verification. The Spanish scientific community remains for the moment rather cautious in the face of these discoveries, stressing that data crossovers will undoubtedly be necessary and that the methodology will have to be scrupulously reviewed
Several notably underline the risk of false positives. “Due to the dates and the location, it is too far from everything that has been detected so far. There are cities with more international visitors than Barcelona and they did not detect the virus in their retrospective analyzes of wastewater ”, explains to El Pais, Fernando González, professor of genetics at the University of Valencia.
A first study and possible explanations that do not convince either Luca Cozzuto, coordinator of data analysis at the Genomic Regulation Center in Barcelona. “You have to imagine a very large number of foreigners coming to Barcelona on vacation to leave viral particles in the water, without infecting anyone else. Or there was a hidden epidemic before September. I think these kinds of pretty extraordinary conclusions require very solid evidence, ”she concludes.