How number two became a number one tool for virologists.

From American Public Media, this is Marketplace Tech.

I'm Stephanie Hughes.

Tomorrow marks five years since the WHO declared the COVID-19 virus officially a pandemic.

Tracking the virus has been key to understanding where outbreaks are occurring.

And one tracking tool that had been mostly on the shelf prior to the pandemic is wastewater

surveillance. That's pretty much what it sounds like, testing what you flushed down

the toilet, which eventually lands in what's known as a sewer shed. Molecular virologist Mark

Johnson at the University of Missouri, join me to talk about the advantages of wastewater surveillance.

The big one is that it's comprehensive. A big problem in doing surveys is you're only survey the people that are getting tested.

With wastewater, you're detecting everyone. And pound for pound, it's much cheaper because you can get a read out of an entire community with one sample, which roughly costs about the same as what it would cost to sample one person.

Patient information, of course, is very sensitive.

When you hear about certain winniages in a state,

they often won't give you information beyond the state level.

They'll just say somewhere in Missouri.

With sewer shed, though, you can't be identified to a person,

so it's sort of de-identified so you can share that information.

What are the limitations with us as a technique?

Well, you don't know who it's coming from.

You can only narrow it down to a community.

So, for I put the cryptic lineage is, I mean, I have found scores of these, and I haven't tracked

down a single one of the people.

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