Note that the University of Barcelona study is a preprint and as such has not yet been peer reviewed.
COVID-19 was announced in Wuhan, China in early December 2019 and would reach all over the world later, including Europe. The first case in Europe was announced in France in late January 2020. This chronology on the evolution of the disease may change according to a study led by the University of Barcelona, in collaboration with Aigües de Barcelona.
The researchers detected the presence of the virus that caused the disease in wastewater samples in Barcelona, collected on March 12, 2019. These results, sent to a high-impact journal and published in the medRxiv file, suggest that the infection was present before knowing of any case of COVID-19 anywhere in the world.
This study, which has the participation of researchers from the Enteric Virus Group of the UB Gemma Chavarria Miró, Eduard Anfruns Estrada and Susana Guix, led by Rosa Maria Pintó and Albert Bosch, is part of the sentinel surveillance project of the SARS-CoV -two. This initiative is coordinated by this research group, in collaboration with Aigües de Barcelona and financed by the REVEAL project, by the SUEZ company, to detect the virus in wastewater and adopt immediate measures considering future outbreaks of COVID-19.
An early detection tool.
Although COVID-19 is a respiratory disease, the researchers proved that there are large amounts of the coronavirus genome in the droppings that reach the wastewater. This situation turned wastewater-based epidemiology into a potential tool for the early detection of virus circulation among the population, especially considering the significant presence of asymptomatic people, especially considering the significant presence of asymptomatic and asymptomatic people. that transmit the virus.
As part of the sentinel surveillance project, and after April 13, the researchers analyzed the samples obtained at two large water treatment plants in Barcelona weekly. “The levels of the SARS-CoV-2 genome coincided with the evolution of COVID-19 cases in the population,” says Albert Bosch, professor at the UB Faculty of Biology and coordinator of the study.
COVID-19 cases hidden by the flu
Later, the researchers analyzed frozen samples from months before systematic sampling, which revealed the growing appearance of the SARS-CoV-2 genome between early January and early March 2020, making the chronology of the arrival of the coronavirus to Spain is even earlier: The presence of the virus was detected on January 15, 41 days before the announcement of the first case of COVID-19, which was announced on February 25.
According to the researchers, these results show the validity of wastewater monitoring to anticipate cases, especially considering the significant contribution of asymptomatic and pre-symptomatic carriers in the spread of the virus. “Those infected with COVID-19 could have been diagnosed with influenza in primary care by mistake, contributing to community transmission before public health took action,” says Albert Bosch, also president of the Spanish Society of Virology.
See also: Dutch study indicates the value of wastewater monitoring for SARS-CoV-2 monitoring
“In the specific case of Barcelona,” continues the virologist, “having detected the spread of SARS-CoV-2 a month earlier could have improved the response to the pandemic.”
Analysis of frozen samples from 2018 and 2019
These results encouraged researchers to analyze some frozen samples between January 2018 and December 2019, with the surprising results of the presence of the SARS-CoV-2 genome in March 2019, before any notification of COVID-19 cases in the world. “All samples were negative with respect to the presence of the SARS-CoV-2 genome, except on March 12, 2019, in which the SARS-CoV-2 levels were low but positive, using two different objectives”, says the researcher.
“Barcelona receives many visitors for both tourist and professional reasons,” continues Bosch, “and it is possible that a similar situation has occurred in other parts of the world, and given that the majority of COVID-19 cases show symptoms similar to those of flu, those cases could have been disguised as undiagnosed flu. “
Models in the epidemiological surveillance of SARS-CoV-2
The Enteric Virus Group is also in charge of the scientific coordination of a project on sentinel surveillance of SARS-CoV-2 in wastewater in Spain, financed by the Spanish Ministry of Ecological Transition and Demographic Challenge. This task has the participation of two CSIC groups, the Institute of Agrochemistry and Food Technology (IATA-CSIC) and the Center for Edaphology and Applied Biology of Segura (CEBAS), as well as a group from the University of Santiago de Compostela. . In addition, together with the UB Health Microbiology of Water Related Research (MARS) research group, led by Anicet Blanch, it coordinates surveillance of the same virus in Spanish waters.
Finally, this group also participates in a project to monitor the presence of SARS-CoV-2 in wastewater at the entrance of Catalan treatment plants, financed by the Catalan Water Agency and coordinated by the Catalan Institute for Water Research (ICRA). Another participant in this project is the Research Group on Viruses, bacteria and protozoa of water and food interest (VIRBAP) at the UB.
The study has undergone peer review and is currently published as a preprint in the medRxiv file.
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