Viewing the Curve

We’ve all heard about flattening the COVID-19 curve, but how many of us have actually seen the curve for our own states?

A week or so ago I got curious, but the best I could find for my state, Oregon, was a table listing each day’s new tally of cases.  I could use that to create my own graph, but I wasn’t that curious.

This morning, however, I heard a news report that about half of U.S. states were seeing declining numbers of cases. And the map that went with the report didn’t include Oregon.

Surprised, I decided the time had come to bite the bullet and make the graph. But first I checked Wikipedia, and to my great joy, someone had done the job for me. Here it is again, in case the version above was poorly cropped by your device

Each of these cases, of course, is someone’s life, many of them tragedies. But with that caveat, here are five things I observe from this curve:

  • Oregon went on one of the nation’s stronger lockdowns on March 23. The effect is clearly evident only 5-7 days later. That tracks well with recent reports that the incubation period of the disease is more commonly about 5 days, rather than the two weeks initially hypothesized. That will be extremely helpful information for efforts to use contact tracing to prevent the epidemic from rebounding, this fall.
  • Daily case counts are extremely variable (possibly due to varying reporting schedules for different counties). But the five-day running average indicates that Oregon is indeed seeing a decline in cases, although probably not yet in deaths.
  • One of the things that has characterized the curve for this disease almost everywhere I’ve looked is that it rises quickly but has a long, frustrating tail. If you’re looking for reasons why experts fear a rebound, that’s it. It lurks.
  • What that means is that during this tail, the rate of transmission has been reduced enough to cause the total number of cases to decline–but it’s not declining rapidly, which means we don’t have a lot of margin for error.
  • As states start reopening for business, each under different rules, my guess is that statisticians and epidemiologists will be poring over curves like this, trying to determine which relaxations have minor consequences, and which (five days later) bend the curve too strongly the wrong direction. (The definition of “too strongly,” of course, will be highly debated.)

Meanwhile, I am pleased to live in a state where the vast majority of people have been quietly learning how to carry out their lives from 6 feet (or more) apart, doing so successfully enough that so far, we have been spared a major outbreak.

That doesn’t mean it couldn’t happen here, but there are times I’m quite proud to be an Oregonian.

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