Florida’s peak week for the number of tests and new cases ended on July 17. Even though Positivity on that week was a staggering 19.0%, which screams-out for additional testing, the state cut back on test counts the next week, and for the next five consecutive weeks. Between July 17 and August 28, weekly testing levels dropped by 60%.
It wasn’t until the week ending September 5, in the face of increased positivity, that Florida’s testing counts increased, but modestly, still 53% below the July 17 peak.
Trump has been widely ridiculed in the press for saying that “more testing leads to more cases”. In the common sense meaning of these words that may seem like a stupid statement, but add one word and it becomes completely true: “more testing leads to more reported cases”.
In this post we’re going to estimate the impact of Florida’s decision to cut testing counts in reducing the Confirmed Case count. Here we calculated an alternative scenario where testing remained at the July 17 levels. As you can see in the chart, Floridas actual testing peaked at 459,151, and dropped steadily to 180,465 for the week ending 28 August, and then increased slightly to 216,130.
If Florida had maintained peak testing levels, how many additional cases does this add? That depends on the Positivity Level, i.e. the percent of people tested who test positive. We calculated using the CDC recommended methodology (see this post for a deep dive on how Florida plays games with the Positivity Level it reports on its dashboard).
To estimate additional Cases, we need to estimate the positivity level on the incremental tests. Generally speaking, when the number of tests goes up, you expect the positivity level to go down somewhat, on the theory that the sickest people tend to get tested first, so that additional tests hit a slightly healthier population.
In Florida’s case, this hasn’t always been true. Florida allocates tests not by need, but by county population. This means that tests don’t flow preferentially to the counties with the highest infection rate. Indeed, in a recent county level analysis, we discovered that the counties with the lowest Positivity Rate were actually testing more than the counties with the highest rates. (see Table 2 in this post). Were Florida to increase testing and change its allocation policies so that counties with higher positivity rates received more tests, there’s a reasonable chance Florida’s average Positivity rate would actually increase even as testing counts increased.
Nevertheless, we think it’s unlikely that Florida would change its allocation methods to one that would increase reported case counts. As a result, we decided to assume a similar allocation based on county population alone, and estimated the Positivity as as shown in Figure 2.
The Scenario Estimate in Figure 2 is calculated as follow:
The original tests are carried forward at the observed Positivity rate
Incremental tests within the scenario are estimated at a lower Positivity rate that decreases 10% for each 10% increment over the number of actual tests. In other words, the first 10% of incremental tests (as a % of actual tests for the week) are carried forward at 90% of the observed Positivity rate, the next 10% at 80%, and so forth.
As shown in Figure 3, for the week ending 8/28, the state actually tested only 180,645 people (with a reported Positivity Rate of 12.5%). In our scenario, we “tested” an additional 276,626 and calculated an incremental Positivity rate of 8.0% using our formula. This converted to a total of 459,151 tests at an average positivity rate of 9.8%.
Overall, in the 7 weeks since the peak week of July 17, the State of Florida reported 318,626 cases, instead of the 463,454 we estimated would have been generated had testing levels remained constant. This means that Florida under-reported new cases by more than 46%.
Based on this analysis, there remains some improvement in Florida’s situation. But it’s not nearly as large as normally reported. Note that the lower case count will ripple into other parts of the reporting. In particular, deaths resulting from cases that are not confirmed will NOT be reported in Florida’s official COVID counts, as Florida (contrary to CDC recommendations) does not report probable COVID deaths.
My dad, who’s a holocaust survivor, and 97 years old, curates a blog for his independent living community about current politics. Yesterday he sent me this note. This is my reply to him.
Sections in italics are direct quotes from Scot Atlas’ op-ed piece in the Hill. Given Atlas’ position, this has to be taken as something pretty close to the “official” policy of the Trump Administration and why it’s safe now to reopen the schools (this post will make a lot more sense if you read it first).
My response follows:
We know who is at risk. Only 0.2 percent of U.S. deaths have been people younger than 25, and 80 percent have been in people over 65; the average fatality age is 78. A JAMA Pediatrics study of North American pediatric hospitals flatly stated that “our data indicate that children are at far greater risk of critical illness from influenza than from COVID-19.”
Death is not the only metric. There clearly are pediatric complications of COVID at an unknown incidence. See, for example this article: https://undark.org/2020/09/02/kids-covid-19-long-haulers/ . This is like suggesting to parents “Don’t worry about preventing your kids from catching Lime Disease. No one dies of Limes”.
Kids are contagious to adults, and are frequently low- or non-symptomatic. Kids catching COVID at school are a perfect vector to bring COVID home and getting adults in the household sick.
While we saw more cases in July and August, we are not seeing the explosion of deaths we saw early on. An analysis of CDC data shows that the case fatality rate has declined by approximately 85 percent from its peak.
Again, a focus on death. See above.
CFR is a truly stupid way to judge the effectiveness of the Administration’s response. It’s much better to keep people from getting sick in the first place. The administration focuses on it because it’s the only measure where the US doesn’t look awful.
CFR is substantially understated in the US compared to other countries because, among other issues, our cases are newer and people haven’t had time to die yet. For example, last month the average case in Florida was 37 days old.
“Peak” CFR is presumably referring to the “bad old days” of April and May when NJ and NY were experiencing so many deaths. Those states did a terrible job keeping COVID out of nursing homes. Lower CFR today is significantly because of a younger population in hospitals. Treatments are better, but not 85% better.
Note also that many red states are skimping on testing (to reduce case counts), and not reporting probable deaths. For many states, particularly Florida and other Sun Belt states, the reality is currently worse than it seems. See my piece: Official Misinformation.
We are doing much better with treating hospitalized patients. Lengths-of-stay are one-third the rate in April; the fatality rate in hospitals is one-half of that in April. Fewer patients need ICUs if hospitalized, and fewer need ventilators when in ICUs.
I suspect a lot of this ties to the fact that a much higher % of cases are now younger (including share of hospitalized patients)
Again the emphasis only on acute illness and death. Most “long haulers” never see a hospital. Again, should we ignore Lime Disease because fewer folks end up in the ICU? The administration’s policies are infecting millions of people. I suspect we’ll be paying the cost in disabilities and increased health care costs for decades. Similar to Opioid Addiction, Diabetes, and Obesity, add COVID to the list of devastating morbidities.
We are progressing at record speed with vaccine development. This is due to eliminating bureaucracy and working in partnership with America’s world-leading innovators in the private sector.
True-ish. However, to be useful in re-opening schools now, we’d need a vaccine now, not next year, which is the earliest it could be delivered in quantity, even if the “end of October” date is real. Frankly, the idea that you can reopen schools now, with limited testing, and high community infection rates is delusional. Especially when many students don’t even think COVID is real. It would be much better to wait for the vaccine to become available before reopening the schools for in-school instruction, especially without adequate testing. Otherwise you risk killing off your most experienced teachers and sickening a generation of parents.
Third, we are leveraging our resources to guide businesses and schools toward safely reopening with commonsense mitigation measures. We must safely reopen schools as quickly as possible, and keep them open. The harms to children from school closures are too great to accept any other outcome.
Same problem as just noted. In many states, positivity rates (when calculated properly) remain above 10%. Florida, for example, is claiming a Positivity rate of 5.83% for the week of 8/23, when the real rate (calculated according to CDC guidelines) was in fact 13.9%. Many of the states most anxious to reopen have positivity rates above 10%. See: https://pandemic-sense.com/2020/09/03/official-misinformation-2/
With this level of infections, I don’t believe any schools will be able to stay open long.
For in-school to work, you need, at minimum, vaccinated teachers and staff, mask mandates, and instant testing available as needed. None of that is required in the current CDC guidelines. Until those elements are available, I believe Atlas is playing politics with the lives of students, teachers, and school staff.
Part 2 – Manipulating Positivity and Reported Deaths
The Trump campaign spews misinformation, trying to convince the electorate that the administration’s response to Corona-19 has been effective. In Part 1, we focused on how (mostly) Republican governors are limiting testing in order to reduce “Confirmed Cases” (Please read first, if you haven’t already).
In that post, we introduced this equation:
(a) [Confirmed Cases] = [People Tested] x [% positive]
Using Florida as a case study, we focused on how the state has reduced its Confirmed Case Count by cutting back dramatically on the number of [People Tested], at a time when best-practice suggests increased testing is warranted.
In this post, we’ll focus on the second variable, [% positive], aka “positivity”, and how it is being manipulated to obscure the reporting of the pandemic, including official reporting of death counts. As we’ll see, these manipulations are creating the appearance of progress against the Pandemic in the run up to the election, but masking the true impact of the disease, and potentially risking thousands of additional deaths.
Why Test at All? A Scenario
There are many reasons for testing, but the most common (and important) is to identify people who are infectious, to isolate themselves, and thereby breaking the cycle of contagion.
Consider this scenario:
Your best friend calls you to say that he’s been diagnosed with COVID. Six days earlier, you hosted him for dinner at your home. Your friend started to feel sick the day after the dinner, procrastinated a day thinking it was allergies, then got tested. Three days later, today, he gets a positive result and he’s called you immediately to give you the bad news.
You’d been reasonably responsible during the dinner party, which was mostly outdoors (though it was a still evening with no wind). He’d spent half an hour conversing with you in the kitchen as you prepared the meats for the BBQ, not always masked, everyone had used the same downstairs powder room, and while you ate outdoors, you drank wine, and talked until the small hours, only a few feet apart.
Should you get tested? I certainly would want to, even if I felt no symptoms, and I suspect most folks would agree, particularly if you’re in a high-risk category (as I am due to age).
So, you go to the testing center and 48 hours later get the good news, negative. However, a few days later you start coughing. So, you get tested again and the result this time is positive.
How does this get reported? According to CDC guidelines, the two tests would both be recorded on the case reporting form, but in the testing summary reports, you’d be listed as a single person tested, with a single positive result. Your personal “positivity” would be 100%.
As you recover, you get additional tests to help determine if you’re still communicable. After 10 days you’re still testing positive, but that result would not change your positivity score. Nor, after another week, when you test negative, does that undo your earlier positive score. It all gets grouped within your case file (and a reason why a Confirmed Case is a thing).
It makes sense.
Most states report positivity following these guidelines. But, Florida mostly does not.
You can figure out the conventional positivity number if you dig into the DOH County Report and calculate it yourself. You can also download the Covid Tracking Project’s reporting, which aggregates the same numbers to the state level. This allows you to compare Florida to other states.
Calculated the CDC-recommended way, Florida’s positivity was 13.9% for the week ending 8/23. This is an important number for several reasons, but specifically, positivity above 10% is considered a dangerous level, and a sign that more testing is needed.
However, if you go onto the DOH’s COVID-19 Data and Surveillance Dashboard, it will tell you that the positivity for the same week ending 8/23 was 5.83%. Huh?
Turns out that Florida does its own, non-standard, and widely-criticized positivity calculation. Essentially, the state counts only a single positive result but, contrary to CDC guidelines, counts all of the individual negative results. These controversial measures also appear on the County Report as the so called “New” Test/Pos/Neg. If you calculate the way the State of Florida does on its dashboard, for the scenario we just discussed, your personal positivity would be 33% not 100%:
The initial negative result
The one positive result (but not the second)
The final negative result
I can see no reason to do this other than to confuse the public, and allow Florida officials to claim a lower-sounding positivity rate. Most folks won’t understand the difference, so that if the state says “positivity” is less than 6%, and many other Sun Belt states are struggling with 10%+, Florida must be doing better, right? The fact that the Trump administration won’t enforce CDC reporting guidelines is another example of how the Administration is placing politics above the national interest.
We saw in Part 1 that Florida was cutting back on total testing numbers in order to reduce the number of confirmed cases. Given the continuing high positivity number (as the CDC would calculate it), you can be sure that there are many people who would like to be tested who aren’t. The question is, are the scarce tests being allocated fairly among the people who need them? Spoiler answer, no.
Allocating Testing in a Time of Scarcity
So how should tests be allocated? Absent scarcity or pricing barriers (i.e. if testing were free), you’d expect test demand to correlate strongly with the number of sick people.
So, an optimal scheme for allocating tests to counties would take into account both the base population of the county, and the positivity rate, in order to allocate more tests to the places where they’re needed.
Florida, instead, appears to allocate testing capacity solely by population. This has the advantage of being bureaucratically defensible, and fairly straight-forward, but leads to some less than optimal results.
As shown in Table 1, for the week ending July 17, counties with above-average positivity tested only 5% more than counties with below-average positivity. For the week of August 27, it was even worse, where the counties with higher than average positivity only managed 3% more testing.
Table 2 breaks this down for counties with the highest and lowest Positivity rates for 8/27. Column 5 of this table provides a Positivity Ratio of the 8/27 and 7/17 percentages. A ratio >1.0 means that positivity increased, <1.0, that it dropped. As a state-wide average, Florida’s Positivity dropped to 12.45% on August 27 from 17.89% on July 17, a 0.7 ratio.
Despite the drop state-wide, 18 of the 20 highest-ratio counties on 8/27 had experienced a Positivity increase. By contrast, 10 out of 10 of the lowest Positivity experienced a decrease at the state-average-rate or better.
In terms of testing rates, counties with Positivity Ranks 11-20 were particularly badly served by the state’s allocation methods, achieving only 589 tests/100k during the week. Equally unfair, the 10 counties at the bottom of the Positivity Ranking were able to test the most at 871/100k, 19.4% higher than the state-average testing level of 729/100k, and 47.9% higher than Counties 11-20 could achieve. This is far from optimal.
Why does the state allocate tests so inflexibly? I’m speculating. But realize that if the state were to allocate extra tests to high-positivity counties it would translate to a higher Confirmed Case count.
Impact on CFR
The Trump administration puts a big emphasis on the Case Fatality Rate, i.e. the percentage of Confirmed Cases who eventually died from COVID.
We did a deep dive on CFR a couple of weeks ago (Is FL 5x better than NJ?) which I don’t want to repeat here but is well worth reading. However, it’s worth noting a few key points:
By reducing Confirmed Cases, the State of Florida is also reducing Confirmed Deaths
Florida doesn’t follow CDC guidelines and does NOT report Probable COVID deaths as part of its official total. So, this misinformation is lowering the official death count substantially.
This means that many Florida COVID deaths won’t be reported explicitly, and will only be understood over time, as excess deaths are identified and analyzed. This is slow process, especially if death reporting is trickling in. It will always be subject to gas-lighting and denial by the political powers that be.
In mid-August, I estimated probable COVID Deaths for Florida as an additional 47% on top of Confirmed Deaths. This was based on the CDC’s excess death estimates in July and early August, based mostly on Confirmed Cases created during a time when Florida was NOT purposefully cutting back on testing. Based on this current testing and reporting practices, excess deaths are likely to increase markedly. Keep in mind, however, it won’t be clear until mid-October at the earliest, given the long lag time between infection and death, particularly for the younger patients that Florida is infecting.
The State of Florida needs only keep-up this fiction, that the situation is improving, viable through the election. I hope this article will encourage more folks to dig deeper and expose what’s really going on.