Chronicles of the Curve

How to Interpret King County's Latest Coronavirus Numbers

Where we stand as summer winds down.

By Benjamin Cassidy August 31, 2020

If you're trying to temper a chronic case of doom-scrolling, or just starting your weekends early these days, you may have missed an encouraging bit of news on Friday. The Washington State Department of Health released a situation report that noted King County's coronavirus cases have plateaued of late. The all-important effective reproductive number, or the average number of people a case would infect, has dropped below one, a sign that cases may decline for at least a little while here. Of course, we shouldn't let up on social distancing yet, or anytime soon. "It remains critical that we limit the size and frequency of our social gatherings, wear face coverings and stay home when we are sick," says state secretary of health John Wiesman.

And before you get excited, parents, the official was not keen on restarting in-person learning. "A continued plateau of cases is not enough to safely open schools,” Wiesman added.

But after a summer that started with a precipitous rise in cases, an easing of our local coronavirus toll is a welcome development as we approach Labor Day and venture into a gloomy flu season. The report shows that daily positive tests, hospitalizations, and deaths in the county have dropped or flattened out recently. Public Health—Seattle and King County's "Key Indicators" dashboard also backs that trend.

Importantly, though, our local health authority's data suggests that testing still needs to improve, both in frequency and in the amount of time that lapses between illness onset and swabbing. Then there's the matter of total cases. While King County's local case rate has steadily declined since late July, it's currently much higher than in late May and early June. In those halcyon days of reopening, our local number hovered just above 25 cases per 100,000 people. Our latest number is 82.

Comparing case numbers over the course of the pandemic can be treacherous; the country's botched testing rollout and contact tracing woes ensured that early counts did not reflect the disease's true spread. But here's the bottom line: We're in a much better position than we were in March, even though daily case counts earlier this summer topped those in the spring. According to the Institute for Disease Modeling, "recent prevalence levels are still considerably lower than those from late-March."

Avoiding a Florida-level outbreak isn't all good news. As of August 10, the research center's modeling suggested that just 3.5 percent of the county had suffered a case of coronavirus.  With more than 95 percent of locals susceptible to the virus, "King County is still capable of sustaining an explosive epidemic," the institute asserts.

How do we prevent that from happening? You already know: by wearing masks and social distancing. At the state level, there are signs we're letting up on both. The Institute for Health Metrics and Evaluation's mask usage tracker for Washington has shown a slight reduction in face coverings, and mobility is on the rise.

So, use that pool noodle this coming weekend to stay six feet apart, not pat yourself on the back.

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