Research shows that sewage in large cities should be routinely tested to provide an early warning system for future outbreaks of lethal disease and pandemics and to be part of ongoing Covid-19 surveillance. This type of surveillance should probably be extended beyond major cities.
news/environment/sewage-in- cities-offers-chance-to-warn- of-future-virus-outbreaks-1. 4454739
Testing of sewage offers a relatively economical way to look for pathogens in an area. And it would be effective as part of an early warning system and long before reports of individual illnesses.