According to the researchers, these results show the validity of the surveillance of waste waters to anticipate cases, specially considering the significant contribution of the asymptomatic and pre-symptomatic carriers in the spreading of the virus. “Those infected with COVID-19 could have been diagnosed with flu in primary care by mistake, contributing to the community transmission before the public health took measures”, notes Albert Bosch, also president of the Spanish Society of Virology.
“In the specific case of Barcelona –the virologist continues–, having detected the SARS-CoV-2 spread a month before could have improved the response to the pandemic”.
Analysis of frozen samples from 2018 and 2019
These results encouraged the researchers to analyse some frozen samples between January 2018 and December 2019, with the shocking results of the presence of SARS-CoV-2 genome in March 2019, before any notification of COVID-19 cases in the world. “All samples were negatives regarding the SARS-CoV-2 genome presence except for March 12, 2019, in which the levels of SARS-CoV-2 were low but were positive, using two different targets”, says the researcher.