Kansas COVID-19 Update, Week 3

Updated Aug 3: The test positivity rate cited below (18.6%) appears to be an error. After taking a deeper look at the Johns Hopkins data, it includes one day (July 27) in which test positivity was reported to be 109.7%. This is obviously impossible (you can't have more than 100% of tests come back positive), so there's something wrong with the data on that day. Test positivity on the other days in the rolling average are 11.2%, 10.8%, 10.8%, 11.6% and 12.5%. So the true number is probably somewhere between 10.8% and 12.5%, which is closer to what it was last week. Still not good, but much better than 18.6%.

The format has changed a bit with this week's Kansas COVID-19 update. Only one of my key stats was "bad" compared to the week before, but it was SO bad that it has skipped right to the "ugly" category. It is a truly shocking number, and one I hope is a fluke, or a data error. As a palate cleanser, I've included another "bonus" section on a single county.

The Good: Once again, Kansas' reproduction rate, or Rt, has ticked down a bit, now to 1.07. Until there is a vaccine or an effective treatment, getting that Rt below 1.0 remains our best chance of containing the virus. (Rt below 1.0 means every infected person spreads the virus to fewer than one other person, on average, which would cause COVID-19 to slowly die out for lack of new hosts. Rt above 1.0 means the virus' spread is increasing). If Rt is decreasing, that probably means more people are wearing masks and social distancing. 

The Neutral: ICU admissions were stable this week, with at least 98 COVID-19 patients in intensive care and 36% of beds available on July 30 (the same numbers as on July 23).

The Ugly: According to Johns Hopkins, the percentage of COVID-19 tests that came back positive in Kansas jumped from 11% last week to 18.6% this week. If that's accurate it means Kansas is not only far from the World Health Organization's standard of 5% or less, but it's tied with Arizona for the fifth-highest test positivity rate in the country. It's also disheartening in that it means we're probably missing a lot of cases and that drop in the Rt might be a mirage caused by hidden infections. 

A quick clarifying note: many Kansas media outlets, when they report test positivity rate, use the figure reported by the Kansas Department of Health and Environment, which is much lower (9.5%). But KDHE appears to be calculating test positivity based on the cumulative number of all tests in the state since the beginning of the pandemic (now almost 300,000). That's not wrong, but it does mean that the percentage isn't going to move much from week-to-week. I prefer to look at Johns Hopkins' number because they're calculating test positivity based on a rolling average of the last seven days of testing. That provides a more current snapshot of the situation, but it also makes the positivity rate more susceptible to weekly fluctuations in testing. 

For example, there has been a lot of press lately about long wait times for outpatient testing done at private labs (mostly Quest and LabCorp). Kansas depends heavily on those labs (they've recorded 70% of the state's positive cases, so far). If their results were really backed up last week and most of what was actually reported were results from hospital inpatient labs, that might skew the test positivity number higher (because patients sick enough to be hospitalized are more likely to have COVID than outpatients). But still, 18.6% is a number that should cause all of us to sit up and take notice. We need more testing in Kansas.

Bonus: At the end of May, Sedgwick County had its test positivity rate down to about 1%. But then the shops, restaurants and bars opened back up and the rate quickly ballooned to about 14% by July 23. Things were going the wrong direction. At one point in mid-July, Wichita's hospitals estimated they had only eight ICU beds available. But since July 23, the test positivity rate has made an abrupt downward turn and is below 12% and falling. What happened? Here's one theory: on July 8, the Sedgwick County health officer ordered residents to wear masks in public areas. Almost exactly two weeks later (the maximum incubation period of the novel coronavirus) the county's test positivity rate began to go down. It's impossible to prove that the mask order caused the downturn, but the timing matches up. Sedgwick County still has a long ways to go, but it's now trending in the right direction, and, as I wrote last week, trends are everything with outbreaks of infectious disease.