Covid in Barcelona March 2019
Most COVID-19 cases show mild influenza-like symptoms (14) and it has been suggested that some uncharacterized influenza cases may have masked COVID-19 cases in the 2019-2020 season (11). This possibility prompted us to analyze some archival WWTP samples from January 2018 to December 2019 (Figure 2). All samples came out to be negative for the presence of SARS-CoV-2 genomes with the exception of March 12, 2019, in which both IP2 and IP4 target assays were positive. This striking finding indicates circulation of the virus in Barcelona long before the report of any COVID-19 case worldwide. Barcelona is a business and commerce hub, as well as a popular venue for massive events, gathering visitors from many parts of the world. It is nevertheless likely that similar situations may have occurred in several other parts of the world, with circulation of unnoticed COVID-19 cases in the community.