I keep waiting for an end to this U.S. wave of COVID. I keep being disappointed. And now, I keep trying to get used to that.
The US is back to 30 new COVID-19 cases per 100K per day, more-or-less unchanged over the past seven days. Unchanged for more than a month, when you get right down to it.
Data source for this and other graphs of new case counts: Calculated from The New York Times. (2021). Coronavirus (Covid-19) Data in the United States. Retrieved 6/24/2022, from https://github.com/nytimes/covid-19-data.” The NY Times U.S. tracking page may be found at https://www.nytimes.com/interactive/2020/us/coronavirus-us-cases.html
Worse, we’ve lost any clear downslope for this wave in the U.S. Northeast, region. That has been the bellwether for this Omicron-II (BA.2.12.1) wave.
That statement is no longer operative. (Just a bit of stray Watergate humor, for those of you old enough to recognize that. That’s Watergate-speak for “I lied”. Or, more charitably, “I was mistaken” or “I changed my mind”.)
You can circular-file all my prior happy-talk about how this will soon be over, because the Northeast led the wave and COVID cases are falling there now. That statement is no longer operative.
I also note that the lingering nature of this most recent wave isn’t just a U.S. problem. The Omicron or Omicron-II (BA.2.12.1) or Omicron-III (BA.4 and BA.5) wave seems to be lingering at fairly high daily new case rates in a lot of industrialized (formerly, “first-world”) countries.
Source: Our World in Data, accessed 6/24/2022.
You have to wonder if there’s some common causality there.
The grim implications of immune escape, or return-to-normalcy Catch-22
N.B.: “Immune escape” is a term-of-art describing a micro-organism that evolves to be able to avoid being stopped by the human immune system. It evolves to escape the defenses set up by the immune system.
Yesterday I looked up the only data I can find on the COVID-19 re-infection rate. Re-infections currently account for 14 percent of all daily COVID-19 cases in New York State.
That has been rising, but my conclusion is that since the start of the Omicron wave, that has merely risen in proportion to the fraction of the population that has been infected.
In other words, it’s the exact same phenomenon as the increase in “breakthrough” infections during the initial vaccination push last year. You are seeing more reinfection (breakthrough) cases because more people have some prior infection (have been vaccinated).
The other implication is that most of the cases showing up now are, in fact, new infections. At least as far as the official statistics are concerned. (All of this is based on infections officially reported to New York State department of health. I’m pretty sure the reinfection rate is calculated by matching person-level records over time to find those with a prior recorded infection).
But I failed to do one more relevant calculation: Based on the observational data, how much protection does a prior infection provide? The short answer is, not much.
You can get estimates of that from several sources, but it’s easy enough to gin one up for New York. Based on the official counts, something less than 25% of New York State residents have had some prior infection with COVID-19. And now, reinfections account for 14% of daily new infections. The upshot of that is that people with some prior infection are about (14/25 =) 60% as likely to pick up a new infection, compared to those who have never been infected before.
That’s a crude estimate, for several reasons. But along with the known ineffectiveness of vaccines at preventing any new infection with Omicron, I think that fills in the gist of the picture. Which I will now summarize as follows:
I: The high degree of immune escape means that nothing about your immune system — not vaccination, not prior infection — provides you with significant protection against a new infection.
You get pretty good protection against having a severe infection. But you get next-to-no protection against picking up any new infection with COVID-19.
But that means where back where we were at the start of the pandemic. If neither vaccination nor prior infection provides (significant) immunity against new infection, that leaves COVID-19 hygiene as the sole effective barrier to continued spread. Wear a properly fitted N95 and stay out of crowded indoor spaces, and you reduce your chances of infection more than if you got vaccinated and did none of that.
Which brings me to my second point. If what I just said is true, then we reach the following:
II: Return-to-normalcy Catch-22. If COVID-19 variants have a high enough degree of immune escape, by attempting to return to normalcy (ceasing all COVID-19 hygiene), we ensure continued high levels of circulation of COVID-19. That is, we ensure we’ll never reach that hypothetical “endemic” level where COVID-19 cases are few enough to be ignored.
In effect, by attempting to return to normalcy, we prevent a full return to normalcy. There will be no return to normalcy, in the sense that COVID-19 will be rare enough — at least at some times of the year — that you can just forget about it, for all practical purposes.
That statement is no longer operative. Now ponder the deeper implications of this.
Remember “herd immunity”? That only works if you can acquire significant immunity from infection. If you can no longer build up immunity to COVID-19 — neither vaccine nor prior infection provides much protection against any case of Omicron — that concept no longer applies.
Remember “endemic COVID”? OK, sure, maybe we’ll never get rid of Omicron, but we can at least expect that it will be driven to low enough levels that you can forget about it for a while. It will become “endemic”. But that, too, only works if the population can acquire significant immunity against some new infection. (Or, as with China, if COVID-19 hygiene is rigidly enforced so as to stamp out any outbreaks.)
On one end of the spectrum you have a disease that’s a one-and-done. A disease where you can only got it once, then you’re immune. Or where there is some highly effective vaccine. That’s a disease where the classic herd immunity concept applies, and that’s a disease that can be driven down to some low, endemic level. Think whooping cough, say, or polio.
Call the first pole “true herd immunity”.
At the other end of the spectrum you have some hypothetical disease with perfect immune escape, where prior infection or vaccination provide no protection. That’s a disease that can, in theory, circulate at high levels in the population forever. The more infectious it is, the higher the steady-state fraction of the population infected at any one time.
Call the second pole “forever war”.
And between those two poles sits Omicron and all its variants.
In hindsight, the history of the pandemic can now be seen, in part, as COVID-19 starting out somewhere near that first “herd immunity” pole, and evolving toward that second “forever war” pole.
This could all change if something intervenes to prevent that immune escape. A better vaccine, say, or maybe once you’ve had BA.4 or BA.5, you have some higher degree of immunity against another infection.
But until we see that, the fact that the Omicron wave appears to be lingering, all around the world, may not be a fluke. It might just be the way the world is going to look, from now on. Maybe a low, ignorable “endemic” level of circulating COVID was as much of a pipe dream as herd immunity was.
Finally, now that I look around a bit, I realize that this is not a new revelation, and that some epidemiologists have been pointing this out for some time now. The discussion above isn’t out of the mainstream of scientific thought at all. It’s just taken me this long to figure it out for myself.
