Post #1456: COVID-19 trend to 3/11/2022: 11 and falling more slowly.

Posted on March 12, 2022

 

This post finishes out the data week.  The U.S. has not yet hit a bottom for new case counts.  We stand at 11 new COVID-19 cases per 100K population per day, down 23% in the past seven days.  Half the states are now in the single digits of daily new cases.

The rate of decline definitely appears to be slowing, but it’s hard to point to any obvious culprit.  If I had to guess, much of the slowdown is occurring because case counts are beginning to rise again in two large states:  New York and Texas.

The disconnect between the U.S. experience and that in other countries continues to widen.  In the U.K., cases are going up, but it now appears that the case mortality rate for Omicron is below that of common flu.  In the U.S., reported cases are falling, but the estimated case mortality rate for those cases is still far in excess of flu.


US trend

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 3/11/2022, 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

These are the same graphs I’ve been presenting for the past few months. I’ve re-based them to start at the peak of the Omicron wave.  As you can see from the lower graph, the rate of decline continues to slow — that dark blue line is once again pulling away from the constant-growth-rate red line.

Just why that’s happening is not immediately obvious.  There is still a nice positive (?) correlation between current case count, and rate of decline in case count.  That is, on average, the states with the fewest daily cases are still seeing the most rapid weekly declines in cases.  It’s even more pronounced if I toss the outliers/influential datapoints.

But the U.S. average depends quite heavily on just a handful of high-population states.  And in the second graph below, we can see that two of the largest states (TX and NY) seem to have reached a short-term bottom for their daily new case counts.


U.S. Omicron cases are falling, but case mortality rate remains high.

I’ve pointed out that case counts are rising fairly rapidly in the U.K.  One of my brothers lives in London, and attributes that to the public’s reaction to the late-January removal of mask mandates. Almost no one in London is using masks now, not even in crowded, enclosed spaces such as the London Underground.

Source:  Johns Hopkins via Google search

To which I would add my guess, which is that the spread of son-of-Omicron (BA.2 the more-contagious variant of Omicron) has increase rates of transmission as well.

In any case, new case rates in the U.K. are back to where they were five weeks ago.  And at present, the U.K. — with about one-fifth of the population of the U.S. — has more than twice the number of daily new COVID-19 cases reported in the U.S.

But here’s the odd part.  An analysis reported by the Financial Times of London shows that the case mortality rate for Omicron in Great Britain is now similar to that of flu in the U.K.

Source:  The Financial Times

Here are the actual numbers, reported by the Weather Channel.

Source:  The Weather Channel

Just to double-check, here’s the U.K. deaths data.  With more than twice as many new cases as the U.S., the U.K. has about one-tenth as many current deaths:

Source:  Johns Hopkins via Google search

In fact, if I put a two-week lag between the U.S. count of cases and deaths, I find that the U.S. Omicron case mortality rate is now about 1.5 percent.  That compares to a flu case mortality rate, in a typical U.S. flu season, of around 0.13%.

There are almost certainly differences in definitions and methods for how the CDC defines those case mortality rates, and how the U.K. health authorities do that.

That said, in the U.K., it now appears COVID-19 has about the same case mortality rate as flu.  And in the U.S., COVID-19 has more than ten times the case mortality rate of flu.

And — coincidence or not — on a per-capita basis, the U.K now has about 10 times as many COVID-19 cases reported as does the U.S.

I’m really not sure what to make of that. So I’ll just recap the facts and leave it at that.

In the U.K., new cases are now rising, and they show about ten times as many new cases per capita as the U.S. does.  Meanwhile, the average mortality rate for those cases appears no different from what the U.K. normally sees for flu cases.

By contrast, in the U.S., new cases continue to fall at a pretty good rate.  On paper, we have one-tenth the new cases per capita that the U.K. does.  But the apparent mortality rate per case is easily ten times what the U.S. normally sees for flu.

As an afterthought, I’m not the only one to have noticed the un-linking of cases and deaths in the U.K.   (See this analysis).  So far, all I can conclude is that they’re as confused by this as I am.