President Trump loves to cite the statistic Case Fatality Rate (“CFR”) as proof the US response to the pandemic is the “best in the world”. His choice is not accidental. If you look carefully, he’s cherry-picked just about the only statistic where the US doesn’t look awful relative to most other advanced countries. He suggests this difference is because US hospitals are more effective than other countries. It’s a lie.
CFR is actually a terrible “top-line” measure for pandemic response effectiveness. The ultimate goal is to keep people from dying or becoming disabled. If you can keep people from getting sick in the first place, it’s much better than curing them, as they don’t suffer, don’t risk permanent health impairment or death, and society avoids spending resources for treatments that are no longer necessary.
If you want a single statistic to measure response-effectiveness (as Jonathan Swan pointed out in his famous HBO/Axios interview), Deaths/100,000 population is much better than CFR. But on this measure the US looks mediocre in comparison to many other countries. And you still have to take into account likely future deaths (not just those which have already occurred). Recognizing the infections are spreading in the US faster than any other advanced country, the US’ death rate is likely to end up among the worst. So, of course, Trump ignores it.
But, even setting all of that aside, the US “lead” in CFR is largely illusory. To illustrate why, we’ll contrast Florida’s CFR to New Jersey’s, a state whose battle with the pandemic resembles the pattern in many of the early-hit European countries, much more than Florida.
What is CFR?
CFR is a simple ratio: [Deaths] / [Cases]. A “naive” CFR calculation looks like this:
Calculated this way, it turns out that New Jersey has the second highest CFR in the US (after Connecticut). No wonder Trump loves to talk about Florida when he promotes his views on CFR.
Do you believe that Florida’s hospitals are 5x better than New Jersey’s in curing COVID? Or is something else going on here?
The short answer
The short answer is, “Yes! A lot of things are going on.” We’ll expand on each of these points, but here are the key explanations for the differences:
- Florida cases are made up of significantly younger people than New Jersey’s. This translates directly to a lower death rate.
- Florida’s cases are newer than New Jersey’s, so a higher percentage have yet to die.
- Florida is currently generating new cases at a much higher rate, temporarily lowering CFR even more.
- New Jersey reports both confirmed and probable COVID deaths, while Florida reports only confirmed deaths. This significantly lowers the apparent CFR for Florida.
- New Jersey was unlucky. Or, you could say, badly located, or made serious mistakes (really, all of the above). Given the once-in-100 year nature of this pandemic, imo, they amount to nearly the same thing.
Florida Cases are Younger
Younger people die from COVID at a much lower rate than older people. In New Jersey, 30-year-old’s died at a rate of 0.22%. Folks aged 80+ have died at a rate of 37%! (Note 1)
A major reason for Florida’s lower CFR is its median age for Confirmed Cases is about 10 years younger than New Jersey’s. As shown in the table, if we apply the New Jersey CFR for each age segment to Florida’s distribution, New Jersey’s overall CFR would decline from 7.7% (as it stood on July 30) to 4.8%.
|Age||NJ CFR||% NJ Cases||% FL Cases|
Florida Case Distributions from Florida Covid Action Master File 8/14/2020. FL age categories converted to NJ categories using a straight-line annual distribution within each FL age-segment.
Note that many European countries have significantly older populations than the US. It’s clear that comparing aggregate CFR from one jurisdiction to another without understanding the underlying age distribution can be very misleading.
More Florida cases haven’t yet died
As of 8/12, the average New Jersey case was 104 days old, while the average Florida case was 37 days.
Once a case shows up in the statistics, it takes a surprisingly long time for the corresponding deaths to occur and be reported. Half of case fatalities take place within 15 days from the date they’re first recorded. Add 7 days delay for the death to show up in the reports, and you’re up to 22 days for half of the deaths to be reported. The next 25% take another week, but then the final 25% trickle in over about another month. For our analysis, we assumed 100% of deaths would be counted after 57 days. (Note 2)
Based on this distribution, of the 557,000 Confirmed Florida Cases on 8/12, 201,000 (36.1%) had yet to resolve into either a death or a recovery. Contrast that to NJ where only only 9,213 (4.9%) are unresolved. Source: pandemic-sense.com original analysis based on Covid Tracking Project Data from 8/12/20.
Most European countries are in a similar situation to New Jersey, with a much older set of cases, which are mostly resolved, in comparison to the US.
Florida is currently generating new cases at a high rate
While related to the previous point, a high rate of new cases also inflates the denominator of the ratio, reducing the CFR even more, albeit only temporarily. Florida added over 48,000 cases in the 7 days from 8/6-8/12: 8.6% of its total cases to date. By contrast, New Jersey added only 2,611 during the same period, 1.4% of its total.
Unlike deaths, which take a while, Florida’s 48,000 cases hit the denominator immediately, reducing apparent CFR. As long as Florida continues to add cases at a high rate, its CFR will always appear lower than its true rate.
New Jersey is experiencing the opposite phenomenon. On July 31, CFR was 7.7%. Over the next two weeks, deaths from old cases continued to trickle in, while relatively very few new cases were added. As a result, CFR increased to 8.5%.
Does that mean NJ is doing a worse job treating its COVID patients? Of course not. Anyone successfully dealing with the virus is eventually going to experience an end-phase when CFR will increase. It’s another reason why it’s stupid to rely on CFR as a sole measure of success.
Florida Doesn’t Report Probable Deaths
The CDC recommends that states report both probable and confirmed deaths in their COVID statistics. New Jersey does so, Florida does not.
What’s the difference? A “Confirmed Death” means a positive COVID test result was received. A “Probable Death” means the deceased was diagnosed by a medical professional as dying from COVID, but not confirmed by a test.
New Jersey added 1,854 probable deaths to its tally on June 25, and continues to report probables, now no differently from other deaths.
Florida does NOT follow the CDC guidelines and reports only confirmed deaths. Realize that this is part of a consistent pattern by Florida’s government to obfuscate what’s actually going on in the state. It gives them the flexibility to cut back on testing (thereby managing the apparent case growth) without CFR exploding. See our post, Faked Out, Not Fake News
To try to estimate the impact, we took a careful look at the CDC’s published “Excess Death” rates, shown in the chart below.
In the chart, each green bar represents total deaths from all non-COVID diseases for a single week, starting 1/1/2017 through 8/1/2020. The orange line shows the 95% confidence level for each date: if total deaths exceed this line, there’s less than a 5% chance that this occurred by chance. A red + on the chart means this confidence level was exceeded. The blue bars show reported COVID deaths separately, which get added to deaths from all other diseases.
Both New Jersey and Florida reported their first COVID deaths within a week of each other. Florida’s deaths stayed at a low level for a couple of months, and didn’t “take off” until after Memorial Day. Even then, the take-off appears relatively modest, a fraction of baseline.
New Jersey’s COVID deaths exploded almost immediately after the first death was recorded (so that combined deaths peaked at nearly 3x baseline).
In both states, after “take off,” you can see weeks where non-COVID deaths by themselves exceeded the 95% interval. Given the location on the timeline, these should be considered “probable COVID deaths” which weren’t included in the original COVID death counts. For Florida, we estimated 3,973 Probable Covid Deaths during 2020 through August 1 (Note 3).
However, New Jersey, following CDC guidelines, began reporting probable deaths as part of its regular reporting, adding 1,854 probable deaths on 6/25.
The different practices are obvious when you compare the CDC reported COVID deaths to those reported by the COVID Tracking Projects reports for the same date, 8/1.
|CDC COVID Deaths 8/1/20||7,159||14,140|
|CTP COVID Deaths 8/1/20||7,022||15,830|
|Estimated Probable Deaths|
not included in CTP count
|Estimated Total COVID Deaths 8/1||10,347||15,830|
|Ratio of CTP deaths|
|CTP COVID Deaths 8/12||8,913||15,893|
|Adjusted [Confirmed + Probable]|
COVID Tracking Project (“CTP”)
Taken by itself, adding this estimate of Florida’s probable cases increases the CFR from 1.6% to 2.4%. Of course, it doesn’t stand alone.
NJ was Unlucky
Overall, our comparison of Florida’s vs. New Jersey’s CFR, and normalizing for age differences, is as follows:
|Source of Adjustment||Florida||New |
|“Naive” CFR Calculation||1.6%||8.5%|
|Adjustment for Florida age distribution||—||-2.9%|
|Adjustment for newer cases||0.9%||0.4%|
|Adding in Probable Deaths||0.8%||—|
|Estimated, normalized CFR||3.3%||6.0%|
So far, therefore, we’ve brought the difference between NJ and FL from 5x to 1.8x, which is much less than before but still a big differential. Why do differences remain?
In my opinion, there are a number of factors. As we’ve seen, only some of it relates to the quality of hospital care. That said, most of Florida’s cases are hitting 70 days later than New Jersey’s. That’s an eternity in Pandemic-time, and means — all other things being equal — that survival rates probably are higher right now in Florida compared to New Jersey last April or May. New Jersey hospitals are probably doing equally well or even better, but there aren’t enough new cases to improve the CFR very much.
In addition, when you assess New Jersey, you can’t ignore that it has the highest population density of any state in the US, and is located next to New York City which started as the epicenter of the initial outbreak. Clearly, if you look at the excess death plot, there was initially much earlier community spread in NJ compared to Florida, and a much greater number of un-diagnosed cases.
Particularly bad for its impact on death rate, there was a much more extensive, early spread of the disease into NJ long term care (“LTC”) facilities.
|LTC Residents (2019)||71,162||42,413|
|Licensed LTC Facilities (2019)||688||361|
|LTC Facilities with Clusters > 50 (7/12/2020)||47||281|
|Confirmed Cases in LTC Clusters (7/12/2020)||4,010||29,510|
2019 LTC data from Kaiser Family Foundation analysis of Certification and Survey Provider Enhanced Reports (CASPER) data.
Cluster data from NY Times, 7/12/2020 as classified and geo-located by Pandemic-Sense.com. (Note 4)
In the wake of COVID-19, there’s been a good deal of finger pointing in New Jersey between state regulators and the LTC industry, suggesting poor judgements (e.g. hospitals given priority for PPE), to little oversight, and insufficient/incompetent infection management. Be that as it may, given this once-in-a-century event, it’s not unreasonable to suggest that problems were at least partly due to bad luck. How bad NJ’s situation is compared to Florida is emphasized in the map below (both states plotted to the same scale) which shows the NY Times LTC Clusters.
Overall, our hospitals and front line medical staff are doing amazing work to preserve the health of the US population. They deserve better support than they’re getting.
(Note 1) These low fatality rates should NOT suggest that it’s safe for young people to catch COVID. Long term health effects are unknown for all ages, but there is significant evidence that young people may suffer debilitating morbidities at a much higher rate than fatalities. Young people who get infected can also expand the pandemic by infecting others who are more vulnerable.
(Note 2) There is a tiny, very long tail for COVID fatalities. For analysis purposes we’ve ignored it, but anecdotal reports of people dying from COVID after illnesses lasting 90+ days are not uncommon.
(Note 3) pandemic-sense.com original analysis based on CDC Florida Excess Deaths with and without COVID-19. We examined weeks where non-COVID deaths exceeded the 95% confidence interval by themselves, and estimated probable COVID deaths by calculating the difference between non-COVID deaths and the CDC’s expected deaths from all causes.
(Note 4) Pandemic Sense classified the NY Times cluster data based simply on the name of the institution. The Kaiser LTC data is undoubtedly a somewhat different universe and is not directly comparable (which is why we didn’t calculate percentages combining the two datasets).