This showed up on Google News today:
Source: Google News, accessed 2/20/2022.
I wouldn’t normally pay attention to that. “The news” presents you with a constant stream of scare stories. Any time there’s some credible source, and a scary story, you’re going to see it, whether or not there’s much to it.
I wouldn’t normally, except that I’ve been waiting to see something like that show up.
That’s due to the graph I’ve been updating almost daily. This one, showing how hospitalizations, deaths, and cases have trended since the peak of the Omicron wave:
Source: Calculated from CDC COVID data tracker data. Case death rate is deaths divided by new cases from two weeks’ prior.
Something ain’t right about that. If there were no change in the underlying COVID-19 variant, and no change in data reporting, it ought to look just like the peak of the Delta wave. Like this, with all the lines in sync:
Source: Calculated from CDC COVID data tracker data. Case death rate is deaths divided by new cases from two weeks’ prior.
But instead, reported cases have fallen a lot, hospitalizations not so much, deaths even less (with a two-week lag built into what I’m showing above). And as a result, the case hospitalization rate and case death rate for Omicron appear to be going up.
Source: Calculated from CDC COVID data tracker data. Case death rate is deaths divided by new cases from two weeks’ prior.
On paper at least, the case hospitalization rate for Omicron is just shy of 7 percent, which is what it was under Delta.
Up to now, I’ve been happy to fuzzy-think my way through this and say, well, that’s probably due to missing positive cases. Maybe, all of a sudden, starting with government handout of free tests, home testing is really taking off. And that’s suppressing the official case count. Which then, on paper, raises the apparent case hospitalization rate.
But all along, I have to say that the magnitude of that effect had to be pretty large. Maybe implausibly large. I mean, if the case hospitalization rate has nearly tripled, doesn’t that mean that we’d have to be missing two-thirds of cases? But if we were, wouldn’t that mean a much steeper descent in the case counts?
In other words, I couldn’t quite make the math work out. So I waved my hands and said, must be due to some missing cases.
The other hypothesis is that Omicron actually is getting more virulent. Maybe one of the two growing sub-variants of Omicron in the U.S. is, for reasons unknown, more virulent than the original.
And, of course, it’s not as if those are mutually exclusive explanations. Plausibly, what you’re seeing could be due to some mix of the two.
The upshot is that I’ve been keeping an eye peeled for any indication that the either of the two newer strains of Omicron might be more virulent. I noted that, for reasons unknown, the CDC began breaking out all three strains as of the last round data.
Source: CDC COVID data tracker.
That said, I still can’t make the numbers work out. The peak of the Omicron wave was 1/16/2022. As of the last reading from CDC (above), BA.2 was still just a tiny fraction of all cases. BA.2 could not possibly be causing a huge upswing in the case hospitalization rate yet.
And that makes me wonder about BA.1.1. But so far, nobody has mentioned anything about that being markedly different from the original Omicron strain B.1.1.529.
(BA is the alias for B.1.1.519, the original strain of Omicron. Each dot in the name stands for the next generation of mutations. BA.2 is the second son of Omicron. BA.1.1 is the first grandson of Omicron. )
Finally, in Post #1400-1, I addressed an old and thoroughly incorrect notion, that viruses will get “weaker” as they mutate. You will still see that repeated from seemingly responsible news sources. Search that post for “soundly debunked” to see modern scientific thinking about this.
Evolutionary pressures force successful new variants to be highly contagious. That’s how they displace the prior existing strains. By contrast, the virulence of each new strain is more-or-less random. It’s based on whatever other mutations happen to “hitch a ride” on the set of mutations that allows a new strain to be more infectious than the older one.
As I stated in Post #1400-1 : We got lucky with Omicron. Lucky that it was far less virulent than the Delta strain it displaced. This, in a pandemic where good luck has not exactly been abundant up to now.
The bottom line is that I don’t really understand what’s driving the rising case hospitalization rate. We’d have to be missing an enormous number of cases for that to be due to missing cases alone. But BA.2 is not yet prevalent enough to have had much of an impact on case severity.
That said, I think this issue of severity is well worth keeping an eye on. If what ends up as “endemic Omicron” is both highly infectious and highly virulent, that means we’ll be living in a somewhat different world, going forward, relative to one where the original, milder Omicron strain dominates.
