Over the last few weeks, there's been a pretty concrete way to track the global fear around COVID-19, that new coronavirus that's been spreading around the world.

You can do it by just looking at the Dow Jones Industrial average. It's been headed in basically one direction since the middle of last month, down.

Right, right. And this was sort of the first stage of fear over what the novel coronavirus, I should say, COVID-19, would do to the economy.

Jordan Weissman covers economics here at Slate.

You said first stage.

Are we at a new stage now?

Oh, yeah.

We're definitely at a new stage.

Yesterday, this new stage meant Wall Street's worst plunge in more than a decade.

People at first were worried that they wouldn't be able to get their stuff from factories in China.

Now people are really worried about what's happening here in the U.S., what's going to happen.

For instance, the airline industry is already getting walloped.

You know, you're seeing Southwest say we're going to lose hundreds of millions of dollars this quarter because people aren't flying.

But you can see how it spreads where it's like first there's fewer flights, then there's fewer people in the airport. And then like Auntie Ann's needs fewer people making pretzels.

And then the person who used to make the pretzels can't go to the movies because they don't have the same kind of fluid cash situation.

And you can just see how this thing grows.

Yeah, you start to see the economy kind of grind down in multiple ways.

It's both the supply aspect and the demand aspect of the economy.

Okay, can we fix it? People are trying to figure that out, but, you know, it's tricky. The last time

there was a terrible pandemic that really did damage to the U.S. was 1918, the Spanish flu.

We were essentially working in the era before modern and macroeconomics even existed.

There isn't really a playbook for what we're worrying about right now.

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