Post #1346: COVID-19, taking stock of Omicron

Posted on December 12, 2021


This post is a short summary of where I think things stand as of 12/12/2021.

1:  Omicron appears to be vastly less deadly than Delta.  The first (and maybe) last graph you need to focus on is this one, showing new cases (top) and new deaths (bottom) from Omicron.  For South Africa.  For the entire pandemic.

The key point is that, based on South African administrative data tracking the pandemic, Omicron doesn’t kill people at anything like the rate that prior strains did.  South Africa is now three weeks into their Omicron wave, and the deaths just aren’t showing up.  That’s the empty circle on the lower right.

Source:  WHO.  Items in red are mine.

This does not appear to be some systematic issue with South African death data reporting.  In prior waves, deaths rose almost contemporaneously with cases.  That’s shown below, where I used the Wayback Machine to grab a snapshot of deaths in the middle of the prior South African wave.

Source:  Wayback Machine.  Red notes are mine.

Finally, this is completely consistent with my “two weeks’ lag” analysis from Post #1343.  If I take deaths as a fraction of cases from two weeks back (to account for the time it takes to die and have that death recorded), and factor in the fraction of new cases that are Omicron, that analysis yielded an Omicron death rate that was, for all intents and purposes, zero.

The upshot is that whether you take three weeks of data and say “we should be seeing those deaths rolling in”, or calculate deaths as a fraction of new cases from two weeks ago, you come up with the same answer:  The mortality rate from Omicron cases is a tiny fraction of the mortality rate from Delta.

The reason this isn’t making the news is that everybody knows that deaths lag cases.  Nobody wants to be premature in making this judgment.

But they don’t lag by an infinite amount.  At some point, the fact that almost no deaths are appearing means that, in reality, almost no deaths occurred.

I’ve even seen some statistically naive reporting, in that the number of “excess deaths” in South Africa doubled between October and November.  That was a headline in yesterday’s New York Times.  The only problems with that are a) November mostly predates the current wave and b) excess deaths during quiet periods is the small difference between very large numbers (total deaths and total predicted deaths).   It’s a noisy figure at best.

I’m not going to bother with a full debunking of that because one week from now it will be moot.  Give it another week, and everybody will have figured out that the deaths circled above are missing.

2:  Omicron appears to generate far fewer hospitalizations.  This is another situation where you see a lot of naive reporting of facts, without a lot of thought behind the reporting. 

I went over the key facts in Post #1343.  The key facts are that a) there are relatively few hospital admissions with Omicron, relative to what you would expect based on the U.S. hospitalization rate for Delta, and b) almost all the “Omicron” admissions in South African hospitals are not sick with Omicron.  Per statistics I cited in an earlier post, in one large hospital system, 76% were admitted for something else.  They only discovered the Omicron infections because they test everyone who is admitted.

This goes hand-in-hand with my third point below, the very high fraction of cases that appear to be asymptomatic.  People who know they have an active COVID infection don’t go to the hospital for elective care.  But they are showing up at South African hospitals now, in large numbers, precisely because they don’t know they are infected.

And so, you see a lot of breathless reporting about the huge increase in “Omicron hospitalizations”.  But that is by-and-large a consequence of the fact that there are now a lot of asymptomatic Omicron infections in the South African population.  It does not seem to be a consequence of a lot of people being admitted for treatment of COVID-19.

But this also means that you must fully ignore all the discussion by South African physicians regarding the lower apparent severity of hospitalized Omicron cases now.  That casual impression of lower severity of the hospitalized is part-and-parcel of this same phenomenon.

So, for example, you will see headlines about the low fraction of Omicron cases that are in the ICU, the almost negligible fraction on ventilator, or the very low fraction of Omicron cases that need oxygen.

Ask yourself this:  If they don’t even need oxygen, why are they in the hospital?  Answer:  Because they’re not in the hospital to be treated for Omicron.  They’re in the hospital for something else, and the hospital picked up the asymptomatic Omicron infection.

Based on the reporting of this, I believe I understand why physicians believe that the average hospitalized COVID case is less severe under Omicron.  Persons with an active Omicron infection have to be separated from the general hospital population.  Best guess, all of those persons get housed together in whatever infectious disease ward the hospital has set up for its Omicron patients.   (And this is also why South African hospitals are reporting counts of all persons with Omicron, rather than persons admitted for treatment of Omicron.  As far as they are concerned, both populations have to be housed in the same infectious disease ward.)

Doctor now step into the infectious disease ward and notice that it’s not total bedlam, the way it was in the past.  And so they say, the average person in the Omicron ward isn’t as sick as they were in the past.  And they are right.  But that’s because in past waves, that ward would have been filled with people being treated for Omicron.  Now, it’s mostly filled with people being treated for something else, who happen to have an asymptomatic Omicron infection.

So all that eyewitness reporting from physicians in these hospitals is worthless.  They are being confused by the fact that with Omicron, the typical person in the contagious disease ward is no longer there to be treated for COVID-19.  And, sure enough, few of them are being intensively treated for COVID-19.

3:  All the reporting says Omicron generates mild and asymptomatic cases.  Nobody disagrees.  That suggests that it’s true.  “It’s true” is a far simpler explanation than suggesting that everybody who had had first-hand experience with this is deluded.  And, best I can tell, the large majority of cases are, in fact, so mild as to generate no symptoms.

In a prior post, I had a quote from a South African reporter saying that all hospitals were reporting the same thing.  Nobody was reporting a deluge of severe cases.  But you can take that further, by eye, and highlight that everywhere Omicron has been found, the local authorities have said that cases are mild, so far.

In particular, keep you eye out for reports of a high fraction of cases being asymptomatic.  Here’s why.  In general, severity runs in a spectrum, from least to greatest symptoms.  From asymptomatic cases to death.  If deaths are missing and hospitalizations are low — so there are few cases at the severe end of the distribution — then it’s almost a given that the share of cases that are asymptomatic will be high.

And so, I can find headlines saying that:

India, 54 out of 55 cases so far have been asymptomatic. (December 9, 2012:  Out of 55 cases, one had mild symptoms, the rest were asymptomatic).

Botswana, 16 out of 19 Omicron cases were asymptomatic (December 2, quoting the health minister for that country).

Europe, 212 cases, all mild or asymptomatic. (December 6, 2021).

USA, 42 cases, one two-day hospitalization, the rest mild or asymptomatic (December 10, 2021).

4:  Further evidence that vaccination doesn’t stop Omicron.

This isn’t really new information.  It’s just an extrapolation from existing work showing low antibody response to Omicron in a test-tube.

I went through the basic (test-tube) evidence that the standard two-dose vaccine regiment does not stop Omicron.  There’s now a quantitative estimate from that same group that says the two-shot vaccine should be only 23% effective against symptomatic illness from Omicron. 

That compares to around 85% effectiveness against Delta.

That’s not an actual measurement from the population.  That’s some sort of mathematical model, based on the observed antibody responses in vitro.

There’s still an almost-universal assumption that the two-shot vaccine regiment will largely prevent severe disease (e.g., hospitalization or death).

Conclusion:  A stopped clock is right twice a day.

I was initially skeptical of the argument that Omicron results in milder cases.  Even if so, I would not have guessed that they were milder enough, on average, to make any material difference.

And, early on, the hard evidence for that was lacking.  But the evidence is now beginning to accumulate.  And it surely looks like the average Omicron case is vastly less severe than the average Delta case.

I think this needs to be said plainly:  Just because all the nuts immediately glommed onto this does not mean that it’s wrong.  People who leap to a conclusion without firm evidence, and on the basis of their prejudices, may sometimes be right.

(Think of it this way: They have to be right sometimes.  If they were always 100% wrong, then their opinions would convey useful information.  You’d have a perfect (and therefore) useful “negative indicator”.  But because these are opinions formed in ignorance, that can’t be true.  Ignorant opinions cannot convey useful information.  Therefore, every once in a while, purely by chance, they’ll be right.)

I’ve heard the “law of averages” expressed as “anything will happen, that can”. I think that maybe this is one of those cases.

To me, all the evidence suggests that the spectrum of illness severity of Omicron cases has shifted radically toward lower severity, compared to Delta.  Near as I can tell, on a per-case basis, it’s resulting in:

  1. Almost no deaths.
  2. And order-of-magnitude fewer hospitalizations.
  3. Far higher proportion of cases that are asymptomatic.

If we could choose, we’d swap our current Delta caseload for the equivalent Omicron caseload in a heartbeat.

And, if I’m right about hospitalization — ten-fold fewer — even if Omicron results in somewhat more cases, we’d still be willing to swap.

My bottom line is that things are going to get better here, in the U.S., as Omicron takes over from Delta.  Somewhat more cases, but vastly lower severity per case.  That’s a good trade.

I think it is — purely by chance — exactly as described in my little bit of science fiction (Post #1338:  Embrace Omicron).  I wrote that tongue-in-cheek.  But now I think it’s more-or-less correct.  For us — where we already have a pretty good winter wave in progress — I believe Omicron is going to reduce morbidity and mortality and hasten the end of the pandemic.

Do I dare to use the F-word here?  Why not.  Flu.  Compared to prior strains, I think this is going to be a lot more flu-like in its mortality and hospitalization case rates.

If so, you can be sure that all the right-wingers in the nut-o-verse will be crowing that they knew this all along.  But they didn’t.  It’s not that they were right.  They were dead wrong, and we have the sharply increased 2021 U.S. mortality rate to show it.  It’s that they are stopped clocks, the nature of the virus has changed, and even a stopped clock is right sometimes.

Call me Pollyanna.  Or Pangloss.  I don’t care.  That’s the way the data look to me.

Embrace Omicron.  It’s not as if you have any choice in the matter anyway.