Virologists from the University of Barcelona analyzed old samples of the city’s wastewater. They would have thus detected traces of viral particles in a sample of March 2019.
The new COVID-19 coronavirus appeared in Spain long before its first case in January 2020. The press agency Reuters reports this hypothesis posed by a recent pre-publication study, conducted by Spanish virologists from the University of Barcelona. According to their discoveries, traces of SARS-CoV-2 virus would have been detected in a wastewater sample taken on March 12, 2019 in the Catalan city. “SARS-CoV-2 levels detected were low but positive”, one of the study’s authors, Albert Bosch, confirmed to Reuters. The researcher and his team have been analyzing Barcelona’s wastewater since mid-April 2020 to detect possible resurgence of the pandemic. As a reminder, if an infection with the COVID-19 often remains asymptomatic, the virus still leaves traces: it can in particular be detected in the faeces of patients, which are thus found in wastewater.
Discovery Requires Confirmation
In addition to recent samples, Barcelona virologists have also set out to detect the presence of the virus in old samples. They notably discovered viral particles of SARS-CoV-2 in a sample from January 15, 2020, 41 days before the first case was officially identified in Barcelona. The occurrence reported in March 2019, even before the first appearance of the famous virus in Wuhan in December of the same year, is nevertheless to be taken with tweezers. As Dr. Joan Ramon Villalbi of the Spanish Health Agency for Public Health explains, “When it is only a result, we always need more data, more analyzes and samples to confirm it and not take it for the consequence of a laboratory error or a methodological problem. ” Other retrospective studies of wastewater analysis – notably another, carried out in the Netherlands – did not find traces of the virus dating from before the start of the pandemic. Outside of China, the first international cases were rare even in December 2019. The head of the intensive care unit at the Avicenne hospital in Bobigny (Seine-Saint-Denis), Yves Cohen, said in May 2020 that he had diagnosed a first patient on December 27. According to BBC, the patient’s wife, now recovered, worked in a supermarket at Charles-De-Gaulle airport, where she could have been contaminated and transmitted the virus barely appeared.
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