Tracing Covid-19 Clusters Though The Sewers

MARSEILLE, FRANCE - DECEMBER 21: Technicians from the 'C4 Diagnostics' laboratory analyze samples taken from the wastewater of a retirement home (Ehpad) by Marseille firefighters to detect traces of COVID-19 on December 21, 2020 in Marseille, France. The concentration of the Coronavirus pathogen released in human waste serves as an early warning system for France in the face of the pandemic. (Photo by Arnold Jerocki / Getty Images)