The current timeline for the COVID-19 pandemic begins with a cluster of viral pneumonia cases that was discovered in Wuhan in late December 2019, and reported to the World Health Organization on December 31, 2019. However, as scientists continue to check samples going back through the year, there has been evidence to suggest the virus was moving around as early as March 2019. In Barcelona, wastewater samples have been tested for the SARS-CoV-2 virus. What is the origin of the virus? How and when did it spillover to humans?