Hi, and welcome to COVID Quickly, a scientific American podcast series.

This is your fast track update on the COVID pandemic we bring you up to speed on the science

behind the most urgent questions about the virus and the disease.

We demystify the research and help you understand what it really means.

I'm Tony Lewis, I'm Josh Fishman, and we're a scientific American senior health editors.

I remember you. Welcome back, Tonya.

It's great to be back, Josh.

Today, we're going to talk about tracking COVID through the sewers,

and explain why vaccines for the littlest kids have been put on hold yet again.

There's been more talk recently about using wastewater to detect COVID.

Forgive me, Tonya, about what's the poop on that?

I'm glad you asked, Josh.

Scientists have known for some time that people can shed the SARS-CoV-2 virus in our excrement.

Traces of virus in our sewage systems can often be detected before a surge in clinical COVID cases,

so they can provide early warning of an outbreak.

And they can spot infections from people regardless of whether or not they're showing symptoms,

or if they have access to testing.

What's new is that the CDC has started adding data from wastewater sampling sites

to its dashboard, the COVID data tracker.

The agency first launched the National wastewater surveillance system in September of 2020.

Now they have more than 400 monitoring sites around the country,

and they're planning to add 250 more in the next few weeks.

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