New Mexico Takes a Turn for the Worse

New Mexico, the poster child for successful state-wide vaccination, slipped onto the naughty list last Friday, 16 April. On the naughty list are the states who have seen an increase in the rate of new COVID-19 cases since the beginning of April. The growing list is on the right side of the plot above.

To be fair, New Mexico still has one of the lowest new case rates, about 10 new cases per 100,000 population compared with the national rate of 20 new cases per 100,000 population. The national rate has been falling for the past two days, hinting that the Fourth Surge isn’t that, it’s just a big orbit about the March/April mean rate of 18.9 new cases per 100,000 population. You can see this in the seven-day average phase plot below.

So the national rate is back where it started at the beginning of March. New Mexico, however, like many states that were doing well in March, has seen a slow creep toward increasing case rates in April. This is shown in the plot below. It’s still possible that April will see the rate orbit about the late March/April mean of 8.9 new cases per 100,000 population. See my web page for more info.

The Fourth Surge – What’s up with Michigan?

Zoom plot.

The Fourth Surge may or may not be upon us (more on that below). But it is certainly clear that new COVID-19 case numbers are growing unchecked in a few states. In the plot above, all the arrows pointing up and right – the top-right quadrant – represent states with increasing new cases numbers in both March and April 2021. Biggest by far: Michigan. The 10 April new cases per 100,000 rate of 73.6 is nearly four times the national rate of 20.5 new cases per 100,000 population. You can see it in the plot: the Michigan arrow is almost four times as long as the National arrow. New case rates in Michigan have been growing by two to four additional new cases each day since the start of March. That is from less that 15 new cases per 100,000 each day to nearly 75 new cases per day in just 40 days.

All of the states on the right side list saw an April increase in the number of new cases per 100,000 population. Which means the states on the left side all saw a decrease in April – good news! The states in the lower left quadrant saw decreases in new cases over both March and April. That may be why all their arrows are so short :).

About that Fourth Surge. At the national level, the numbers of new cases in April have erased all the improvements in March, which is why the National arrow in the plot above points down and to the right. But it’s not necessarily a trend yet – new case numbers have hovered around the 20 new cases per 100,000 population before. Clear in the plot below, however, is that the number new cases per 100,000 population just leapfrogged over the somewhat stable orbit in early March. It remains to be seen if this is a trend (that is, a surge) or part of a much bigger orbit around the average March case load numbers. See my web site for more details.

Another Update on the Fourth Surge

Copyright (c) 2021 D.S.Dixon
Data from the New York Times database.[1]

The April uptick looks like it may be settling into an orbit between the early-March orbit and the late-March orbit. If so, that’s a really good thing, and a sign that most Americans are still taking COVID-19 seriously. We are likely beginning to see the benefits of wide-spread vaccination, as well. The individual states are still all over the place in terms of trends. See my web page for more information.

[1]The New York Times. (2020). Coronavirus (Covid-19) Data in the United States. https://github.com/nytimes/covid-19-data

Update on the Fourth Surge

Copyright (c) 2021 D.S.Dixon
Data from the New York Times database.[1]

The first three days of April have seen some movement away from the stable orbit about 17.6 new cases per 100,000 population. This isn’t a surge on the order of the holiday surges from 7 November 2020 to 16 January 2021. As some states continue to see falling new case rates, many states with steady or decreasing new case rates in March have also seen this uptick in April. See my web page for more information.

[1]The New York Times. (2020). Coronavirus (Covid-19) Data in the United States. https://github.com/nytimes/covid-19-data

No new COVID case surge – yet

There has been much talk about a new surge in COVID-19 cases, dubbed the Fourth Surge by CDC director Dr. Rochelle Walensky on 29 March 2021. So I checked it out.

I’ve been watching the dynamics of new COVID-19 cases in the U.S. for several months, posting daily updates to national and state plots on my website. Here’s a plot of the number of new cases per 100,000 population versus the daily change in the number of new cases per 100,000 population as of 25 March 2021 (posted on 26 March 2021).

The data come from The New York Times, based on reports from state and local health agencies[1]. The arrows show the daily changes color-coded by month, starting with January 2021, on the right, and ending with March 2021, on the left. Arrows in the top half point up and right to show increases in the number of new cases, while arrows in the bottom half point down and left to show decreases in the number of new cases. When the number of new cases is changing every day but averaging about the same over time, the arrows form a kind of circle (I call it an orbit). Note the orbit at the far right in mid January 2021, centered at about 70 new cases per 100,000 population.

Let me point out that these data are averaged over 18 days, while the CDC tends to use a seven-day average. The seven-day average tends to be too jittery to track daily changes for this purpose. The jitters in the seven-day average are a result of the various ways that individual states report COVID-19 data, combined with a weird thing that happens with these kinds of data: events tend to be recorded on certain days of the week even if they happened a day or two before.

This plot shows an overall trend of rapidly decreasing numbers of new cases since 16 January 2021, when it peaked at over 71 new cases per 100,000 population, down to around 20 cases per 100,000 population in March 2021. In March this trend ended, however, stalling first at about 20 new cases per 100,000 population, then slowly decreasing to slightly less than 18 new cases per 100,000 population on 23 March 2021.

Then with two days of increases – 24 and 25 March – the trend implied a worsening – a possible new surge? Fast forward to 31 March 2021, shown in the next plot.

Note that the uptick on 25 March was followed by a down tick on 26 March, and the subsequent five days saw a tight orbit about approximately 19 new cases per 100,000 population. Dodged that bullet!

On the national level, anyway, but some states are seeing rapid increases in the new cases that may be a sign of worse times to come. See my website for details.

[1]The New York Times. (2020). Coronavirus (Covid-19) Data in the United States. https://github.com/nytimes/covid-19-data