The Bump Up In Utah

Most of you are aware that COVID-19 cases increased greatly in Utah after the universities started up again.

Here's what they're not telling you (because it's complex) but which a macro student ought to be able to digest. 

Prior to September 10th, the daily measure of case growth over the previous week had hung around 5% for about a month. What's happened since then is not a level shift, but rather a growth shift.†

We are now over 30 days into a sustained shift of that daily measure of week-over-week growth to 10%. 

What does that mean? From March through August, what we saw was a slowly declining growth rate. Even in July, when there were a lot of cases statewide, the growth rate was high but still dropping. It seemed like it had been hit by a transitory shock.

No more.

What we have now is a full-fledged second wave.

Except ... shut up if you ever feel the need to say that out loud. Viruses don't have second waves. People do.

And Utah's second wave is not like its first.

The first wave was characterized by the portion of the population where the infection was thriving figuring out that it didn't like the way things look and slowly learning to avoid infection. 

It's still early, but it appears that our current second wave is in a portion of the population that isn't learning those things at all. Growth rates aren't getting worse. But they don't have to. At this rate we're doubling cases every 10 weeks, and by this time next year everyone in the state will have had it. 

Time to review the lily pad analogy.

† A sustained growth rate shift is exactly what we do not see in real GDP. There, shocks to growth rates are transitory, and fade out after a few quarters. Most of what we observe in real GDP is permanent level shifts caused by those transitory growth shocks. What we're seeing with COVID-19 in Utah is an increase in slope of the level.