Post #1170: Recent COVID case trend is unknown, Delta variant

Posted on July 6, 2021

I wish I knew what the recent U.S. trend in new COVID-19 cases was.  But the fact is that nobody knows.  Today’s data release, with data through 7/5/2021, had data from fewer than 20 states.  I don’t really think that’s enough for constructing a estimate of the current trend.

The fact is that between the states that no longer report on the weekends, the states that only report sporadically, and the July 5th holiday day, there’s really no current information.

In addition, we can probably expect the July 4th holiday to leave an artifact in the data similar to that seen for the Memorial Day holiday.  Some changes in testing behavior and speed of test processing, in addition to the plain fact that the states didn’t report information on new cases.

The upshot is that it may be well into next week before we get another clear fix on what the underlying trend is.

Delta variant incidence

I stumbled across a non-CDC source for information about the current incidence of the Delta variant.   This site is a Federally-funded project based at the Scripps Research Institute.  Based on their estimates, Delta currently accounts for about two-thirds of U.S. cases.

Source:  Julia L. Mullen, Ginger Tsueng, Alaa Abdel Latif, Manar Alkuzweny, Marco Cano, Emily Haag, Jerry Zhou, Mark Zeller, Emory Hufbauer, Nate Matteson, Kristian G. Andersen, Chunlei Wu, Andrew I. Su, Karthik Gangavarapu, Laura D. Hughes, and the Center for Viral Systems Biology Available online: (2020)

The website has some technical problems, but the graph syncs up well with the older CDC data.  The CDC data showed that Delta accounted for 26% of cases, as of roughly June 14.  With a doubling time of about two weeks, that could easily result in the roughly 65% of cases shown currently, above.

To me, that’s something of a good news/bad news joke.  The bad news is, Delta is now the dominant COVID-19 variant in the U.S.  The good news is that outside of a few areas, such as southwestern Missouri, that’s not having a huge impact yet.  Case rates were starting to turn upward in a lot of places, but only modestly.

In any case, only 35 more percentage points to go, and it’ll be as bad as it can get.

Interestingly, the Delta-driven outbreak in Great Britain is continuing apace, and yet Britain is not postponing plans for removing their remaining COVID-19 restrictions.  Almost all new cases in Britain are the Delta variant.

The current rate of new cases in Great Britain is about 25,000 per day.  That would be equivalent to about 150,000 per day in the U.S., or more than ten times the current rate.

The mere presence of the Delta variant does not guarantee an outbreak.  Almost two weeks ago, Germany passed the point where half of new cases are the Delta variant, and they have seen no uptick so far:

I think the upshot of all of this is that we’ll get there when we get there.  Odds are still in favor of a major uptick in new cases, based on the increased infectiousness of Delta.  We were starting to see a broad upward movement in new case counts last week, but it didn’t appear to be centered on the states that the CDC said had the highest incidence of the Delta variant.

Maybe by the end of the week the picture will be clearer.  The US CDC is due to update its state-level estimates some time this week.  Presumably, most states will have reported current counts of new cases.  I’ll reassess at that time.