COVID-19 May 24, 2020

The pandemic marches on.  New cases continue to hold steady or rise slightly, but the death rate continues to fall and continues to follow the Gompertz model remarkably well. If that agreement continues, we will hit 100,000 deaths on or about June 8.  On that date the model predicts 444 deaths per day, which is less than half the current rate.

COVID-19 May 23, 2020

No significant changes in the trends to report.  Here are the data.  Go enjoy the weekend!

COVID-19 May 22, 2020

How about some not so bad news to kick-off the holiday weekend?  The daily death statistics are still on the decrease.  When I saw the minimum values earlier this week I was concerned that they hadn't dropped enough to keep the downward trend going.  But, this week's peak was also lower than I would have expected, so on average things are still going in a good direction.  I adjusted the Gompertz model very slightly upward from 100,000 to 108,000 total deaths in order to better match the cumulative death data.  This assumes that everything continues as it has in the past.  I doubt that it will, but for now we are still following the model.

In contrast, new cases are now clearly showing the average upward trend. I don't have anything more to say about that.

COVID-19 May 21, 2020

I have another very busy day today, but I didn't want to skip another day.  This is going to be short.  There's no significant change in the trends.  The death rate has flattened is essentially flat.  New cases have started to move up very slightly.  I'm waiting for the weekly peak, which should occur today or tomorrow.

COVID-19 May 19, 2020

We've passed through the minimum for the week, and the trends are starting to look more worrisome. Let's start with the Daily New Cases.  Prior to the last week, the maximums and minimums had slowly but steadily been decreasing.  As a result, the number of new cases decreased, on average from about 30,000 per day on April 23 to about 23,000 per day on May 14.  I had noted that this past week's maximum was about the same as the prior week and was skeptical that the upcoming minimum would be low enough to compensate.  Well, the results are in, and not only was the minimum not low enough, but it was higher than last week's minimum.  The trend is now broken and the 7-day average is back on the uptick.  Higher numbers are very likely to come in for the rest of the week if they follow the weekly cycle. This will drive the 7-day trend even higher. I suspect this is just the beginning of what's to come.

Turning to the Daily Death statistics, it looks like the 7-day trend is heading toward a more steady number and that the slow decrease is also approaching an end, but that signal is less robust than for the Daily New Cases.  Since the number of deaths should be a function of the total number of cases, it makes sense that the death statistics should start to reflect the infection statistics.  Unfortunately, the relationship between these two data isn't as tight as it should be, because the availability of testing has an impact on the number of cases that are reported.

COVID-19 May 18, 2020

I know it's tempting to look at individual daily numbers and make inferences about what is happening.  This is especially true if the daily number comports with your beliefs.  As a scientist, it's important to recognize and the short circuit the insidious nature of this confirmation bias.  As an example, the large number of new infections (1801) reported in Texas the day before received a lot of press, and many were quick to jump on that as evidence that there was a cause and effect relationship between that number and Texas's loose quarantine policies.  The number of new cases in Texas yesterday was 785.  That is one of the lowest numbers reported by Texas in the last two weeks.  Will that make the news?  Will those who jumped all over the 1801 number mention it?  The answer is probably no and no. 

It is generally unwise to focus on an individual daily number.  All the numbers must be taken together and understood in the context of the situation.  That situation includes an abysmal testing and reporting system that lacks nationwide standardization.  Daily numbers go up. Daily numbers go down.  I've taken to using a 7-day average because that seems to at least smooth out the weekly cycle that is inherent in the data.  The daily variations tell me that looking at the data with a fidelity shorter than about a week is probably bad data analysis.   If the numbers in Texas are going to respond to their policies, it will show up in the longer-term average.  It's not going to happen overnight, which means it's not going to show up suddenly as a big increase in just one day.  At least it's not likely to turn out that way.

And now, here are the usual plots:

COVID-19 May 17, 2020

Although I post the daily statistics each day, the interpretation of these data really comes down to two days each week: the day of the minimum and the day of the maximum.  If you look at the daily deaths below, you'll see that we hit the weekly peak a couple of days ago. It was much lower than the previous week, which is good because the previous peak was a record high.  And then the minimum value last week dropped it back below the Gompertz model curve.  This drop brought the average back closer to the model.  In the next few days, we'll see what this week's minimum will be.  Will it be lower than the value on May 10?  It looks like it will need to be 600 or below if the average is to maintain adherence to the Gompertz model.

In the meantime, the daily new cases continue the very slow linear downtrend.  Will that continue?  We had a peak a couple of days ago that was close to the previous week.  If this week's low isn't lower than last week then the downward trend will be broken and we will be either steady and increasing again.

More than a week ago I analyzed the increase in testing in comparison to the reported new cases.  Testing is still increasing and it is difficult to tease out what fraction of the trend in new cases is due to the testing.  The more you test, the more cases you expect to confirm, at least up to a point.  The fact that cases have been slowly decreasing could be considered a good sign.

So, the next couple of days will be filler while we await the minimum values for the week.

down to waiting to see where the weekly minimum and maximum end up.  Everything else is filler.