Twice higher than Delta
We were told that “most cases of Omicron” are mild. Well, most cases of original Covid or Covid-19 are mild also. My own Covid was a mild experience as well. (I was 49 when I had it last year) But we know that Covid is dangerous, so we need to look beyond a few “mild” cases who just arrived on planes and did not even have time to die.
Is Omicron really a mild disease? We will consider it here. Before you start, read my yesterday’s article “URGENT — Omicron “variant” likely to be man-made”.
Calculating Case Fatality Rate (CFR)
Case Fatality Rate is the number of deaths of the disease, as a percentage of the number of cases. So, for example, if 1,000 get sick and 15 die, the CFR is 1.5 percent.
Before we delve into the most recent South Africa stats, note that Covid deaths, on average, happen about two weeks after the illness starts. So if you look at death vs case rate graphs, make sure that you are comparing deaths on a given date, to case rates approximately two weeks prior to that date.
You can look at any country using Worldometer, and compute their general case fatality rate, for a particular time period, as follows:
- Look at average weekly number of cases for a given date
- Look at average weekly number of deaths for two weeks later
South Africa’s general Case Fatality Rate is about twice higher than in the United States. The most likely explanation for this is that mild illness is not detected or recorded correctly. It could also be that the standard of medical care in the US is higher than in South Africa. Another, alternative explanation, is that South Africa is much less vaccinated. The higher South Africa CFR could also be due to “all of the above”.
I calculated CFR for both countries using Aug 1-15, Sep 1-15, and Oct 1-15 for cases and deaths using weekly averages for both. I used case average for the 1st of the month, and deaths average for the 15th of the month, to account for the two week lag between cases and deaths.
While in the US the recent case fatality rate is about 1.23%, the CFR in South Africa is 2.58%, based on total deaths and total cases since the beginning of the pandemic. CFR numbers vary over time, somewhat, but recently seem to be similar to the average numbers cited.
The above shows that the US CFR is about half of South Africa’s.
The “Omicron” virus started a new explosion of cases in South Africa. The “cases” graph looks like a vertical wall. The graph ends at yesterday Dec 2, 2021 at 11,536 cases. Today (not part of this graph) we have 16,055 cases, continuing the “vertical wall climb”. Today is not part of the original graph, so I added it in red color.
According to Worldometer, the numbers of deaths for Dec 1,2,3 is 30,21,25 respectively. The cases, conveniently for me, started going up rapidly exactly two weeks ago. Cases for Nov 17,18,19 are 329, 362, 420. Dividing (30+21+25)/(329+362+420), we get 6.8% case fatality rate for these three day periods, spread three weeks apart.
On the basis of weekly averages (deaths ending Dec 2 and cases ending Nov 18), we get CFR of 21/362 = 5.8% CFR.
Note that any calculations of “week averages” for a disease that grows by 40% each day, is inherently prone to calculation errors. There was a strange spike in deaths on Nov 25, likely due to reporting delays, that is NOT part of the latest weekly average. Our calculations here clearly are very tentative and preliminary.
In any case, two of the above calculations show that Omicron CFR is at least double, or almost triple, of what South Africa experienced before. If this translates to the US experience (where we have twice lower CFR), and our CFR doubles or triples, we would get a disease with CFR of about 2.5-3.2%.
If we get an uncontrolled pandemic with a CFR of 2.5-3.2 percent, you can easily imagine the social consequences of this and the pandemonium that this would cause. It is not at all known how vaccination or natural immunity would affect fatality rates, but Omicron looks like a virus that is at least twice as deadly as Delta, and much more infectious for much faster spread.
It seems that in South Africa, Omicron cases increase by 10 times every week. This means that every four weeks, they increase 10^4 = 10,000 times. Note that eventually, exponential growth will slow down and will eventually subside in accordance with “epidemic curve”, but in the beginning the exponential model should give us some idea.
If we have 200 actual cases of Omicron in the US right now, in four weeks we will have 2,000,000 cases and the daily increase would be 800,000 cases per day. This will be enough to get us all scared and force many politicians decisions.
Let your own imagination work here. What do you think will happen if we get a “vertical wall” of cases here with 3% CFR?
Also, forgot to say, make sure that your Christmas vacation reservations are cancellable.