Brown County Case Analysis, January 24th, 2022

Today was a busy day, but I wanted to download fresh WI DHS data to see where things stood.

First, Rt (Figure 1), which is a calculation that projects near-term infection rates. It is a metric developed by folks from Harvard, Yale and Stanford Medical, funded by HHS/CDC. "If it’s above 1.0, COVID-19 cases will increase in the near future. If it’s below 1.0, COVID-19 cases will decrease in the near future." It is the only data source I refer to for future projections, realizing that it may correct or adjust daily.

Today I looked at the State of Wisconsin and Rt for the state is at 0.69 and Brown County is at the lowest level I've ever seen it at 0.50. It had started trending down in early January, but I like to see a trend mature to over 14-days of age before giving it too much weight.

Figure 1

Second, DHS case data, which is trending down across Brown County (Figure 2). I noted last week that testing volume started to taper off, which is always a second indicator that cases would soon follow. That trend has held true. Masking, or lack thereof, does not influence these trends, rather testing volume does. Masking likely reduces the impulse to test continuously, but testing volume is the core driver behind the positive cases.

Look closely at Figure 2 that shows the relationship between testing volume (the top dark blue line) and positive cases (the bottom light blue line). This is because the cycle thresholds the labs process tests at are far too sensitive (between 37 and 40), returning over 50% more positive results as compared to a cycle threshold of 30, for example, like the NBA has switched to using.

There is a misconception by some that putting the masks on at Lineville and Howard Elementary influenced the positive tests. That is a false interpretation of the data. If you look at the other districts, you'll see that they all followed the same trajectories. Figure 3 further breaks down the positive cases by ages 0-9 and 10-19. Green Bay (Red: K-12 mask mandate) is faring no better than any other district (Yellow: K-6 masking, Green: mask optional).

In summary, with the decline in Rt and overall testing volume, cases have now started to trend down. Lets hope these trends continue.

Figure 2

Figure 3

(the sum of these equal the total in Figure 2, ages 0-19)