I think we’re rapidly approaching the end of the Omicron wave in the U.S. I’ll define that as the point at which the daily count of new cases stabilizes at some low “endemic” rate. It’s tough to say that, exactly, as the Presidents’ Day data reporting messes up today’s estimate of the new case trend. Despite that, that’s how it looks to me. We’ll have a better fix on that tomorrow.
As of 2/28/2022, the U.S. stands at 22 new COVID-19 cases per 100K population per day. That’s the same as it was as of last Friday’s data, and it’s only down 11% in the past seven days. But, as noted above, part of that is an artifact of getting past the lack of data reporting on Presidents’ Day.
That said, everything I can see points to a sharp slowdown in the rate of decline of new COVID-19 cases in the U.S. Ready or not, I think we’ll soon know what our endemic level of Omicron looks like.
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 3/1/2022, 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
Winding down these posts
I’m going to stop posting so frequently about COVID-19. I guess I’ll grind it out until the end of the Omicron wave. Then maybe revisit this every Tuesday or so, as all the data series I usually look at get refreshed on that day.
More-or-less everyone seems to have decided that COVID-19 is no longer much of a threat in the U.S. And, right now, I mostly agree with that. In most parts of the country, I think we’re reached a COVID-19 risk level equivalent to that of a typical flu season, for those who are boostered. At least, in terms of risk of hospitalization and death. In addition, new case rates are low enough that hospital systems are no longer stressed. For the first time in more than half a year, there’s no U.S. state where COVID-19 cases occupy 30 percent or more of staffed ICU beds.
For now, let me tie up a few loose ends and point to some things that may change.
Omicron-specific vaccine? One of the big unknowns was whether vaccines could be improved to perform better against Omicron. That question remains unsettled, as of a couple of weeks ago (reference). So there may or may not be a better vaccine in the pipeline. And, as we all know by now, the existing vaccines don’t seem to do much for little kids (reference).
Son-of-Omicron BA.2 variant. CDC now pegs it at about 8 percent of all new cases, up from 4 percent a week ago. That’s via the COVID data tracker, accessed 3/1/2022. So that’s still doubling every week, as a share of new cases. Whether or not that’s going to have any material impact on the trend in new cases is not yet known. Best guess, it’s half-again as infectious as standard Omicron (B.1.1.529).
Cases missing due to rise of home testing. Well, that now doesn’t look to be a dominant factor in case reporting. Or, at least, you can’t tell it from the data. The CDC came out with it’s most recent comparison between estimated true infections (“seroprevalence”). Historically, this was a number somewhat greater than 2.0. Now it’s 1.9. At first glance, the official count of new cases is actually a higher fraction of the true count than it was in the past.
There are two unresolvable problems with this comparison now, with errors pointing toward an “undercount” in the seroprevalence data. One is that immunity fades over time, so at some point, seroprevalence surveys will lose individuals who were infected early on. The second is that re-infections are now common under Omicron. Re-infections count as new infections in the official counts, but … each person can only be counted once in the seroprevalence survey. Last I checked, reinfections accounted for about 8 percent of all new Omicron infections.
Excess case hospitalization and mortality rates on the downside of Omicron wave. Yep, that’s still there. Best guess remains that this is a consequence of waning immunity in the elderly population.
State-level variation in COVID-19 case hospitalization rate. I would love to use local COVID-19 hospitalization rates as indicators of risk. Problem is, they seem to vary hugely. As to why, your guess is as good as mine. All I can say for sure is that the state-level case hospitalization rate varies inversely with the number per-capita number of new cases being reported. That suggests, but does not prove, that there’s a lot of variation in the completeness of data reporting across the states.
