Friday, March 27, 2020

The COVID-19 Trajectory

On Thursday, March 26, the United States took over the top spot for the number of reported COVID-19 cases, exceeding 85,000. It’s important to recognize that reported cases are an inaccurate proxy for actual cases. Some countries may deliberately under-report their rate of infection. Some countries do more testing than others. Regardless of the statistic’s flaws, it’s what we have available.

Being number one is not a status we’d prefer, but it’s one we are likely to keep for a time. Ultimately, India, with its population four times larger than ours, or Indonesia, Brazil, Pakistan, Nigeria, Bangladesh or similar with lesser populations but less-developed healthcare could exceed our overall cases. We don’t wish it on anyone.

Using Reported Cases per Million of Population

Because of the population differences, the raw number of cases does not reflect the status of the disease within a country. Ten-thousand cases in a country of ten million is much more serious than ten thousand cases in a country of one-hundred million. Converting the raw reported numbers into cases per million of population eliminates the effect of population size.

All statistics used in this blog come from I have not attempted to independently verify their numbers, but I believe them to be reliable. As of March 26, the U.S. had a reported case rate of 258 per million. Italy stood at 1,333; Spain at 1,236, Germany at 524. Some countries we don’t hear about in the news have much higher rates: Iceland stands at 2,350 and Luxembourg at 2,321.

The U.S. Prognosis if it follows other country trends.

We are in the early stages of this contagion’s spread. I prepared this chart to illustrate how our rate of reported cases compares with Italy and Germany. Day 1 for each country is the date when reported cases per million of population was approximately 6. Italy (in blue) reached that milestone first and, therefore, has the most days on the chart. Germany (salmon) reached the threshold eight days after Italy. The U.S. (black) had the benefit of an additional week before it crossed the threshold.

Covid-19 Reported Cases per Million Population: Italy, Germany, U.S.

Germany has closely tracked Italy for three weeks. That does not mean we know Germany will continue to follow Italy’s trend. Perhaps their “social distancing” measures will prove more effective, or their healthcare system more robust in stopping the spread of the disease by better testing and isolation of patients with positive coronavirus results.

The United States can take no comfort from this chart. Our rate of increase for the last week has exceeded Italy’s and Germany’s for their equivalent period.

What would it mean if we were to follow Italy’s trajectory? Using their 1,333 cases per million, the U.S. would total 440,000 reported cases at day 30. We would have about 33,000 new cases that day—Good Friday—two days before the President wishes for filled churches on Easter Sunday.

Will it be that bad?

I have no idea. Perhaps the measures many states have taken will be much more effective than Italy’s efforts, and we’ll see our rate of infection slow significantly. But it is also possible that because of the independent spirit Americans are so proud of, large pockets of the country will continue to ignore best medical precautions and our path will continue to worsen.

Below is the same chart, but with Spain added.

Covid-19 Cases per Million population: Italy, Germany, U.S. & Spain

Spain (green) reached the initial six cases per million on the same day as Germany. They did not implement the same precautions, and Spain’s rate per million has already exceeded Italy’s.

These charts should be a precautionary tale. In the U.S. we still have large portions of our population who continue to be exposed. Those working in our hospitals are most vulnerable: we bring the worst cases to them. That is the sharp tip, but underneath are all those who continue to serve so we may live. The folks at the grocery stores, drug stores, Amazon’s warehouses, factories producing masks and ventilators, police, fire, national guard. The list goes on.

We have not isolated those “out in the world” from those in “self-isolation.” That’s why infections are likely to continue for many more weeks. We can hope warm weather will help bring an end, but seeing cases rising in places like Australia and Chile, where summer recently moved to autumn, do not provide comfort.

Over the next days, facts will replace supposition concerning the trajectory of infections in the U.S. Rather than wishing and hoping for life to return to normal in two weeks, we need to concentrate on caring for those most ill and protecting those most vulnerable from contact with anyone infected.

This might be an appropriate time to live the words John F Kennedy used in his inaugural speech. “Ask not what your country can do for you; ask what you can do for your country.”

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James M. Jackson authors the Seamus McCree series. Full of mystery and suspense, these thrillers explore financial crimes, family relationships, and what happens when they mix. False Bottom, the sixth and most recent novel in the series is set in the Boston area. You can sign up for his newsletter and find more information about Jim and his books at


  1. Excellent article. The only quarrel I have with data from Worldometers is that they are continuing to report an incorrect number of US recoveries. The problem seems to stem from New York, which had a sharp reduction in actual cases a few days ago. This resulted in an incorrect number of recoveries (apparently a back calculation from subtracting out the number of deaths). I think the problem might be caused by people fleeing New York, possibly many active cases. Wherever they go to, they may not be properly entered into the reported data for that state. I tried reporting this to Worldometers, but so far they have ignored me.

    1. Interesting information. But from what you've said that doesn't affect the number of reported cases, which is what the analysis is based on.

  2. Right, the analysis is fine. But I like tracking the number of recovered cases in comparison with the number of deaths, watching for the point where those two numbers become equal and then cross. Worldometers is now reporting 2471 US recoveries, Johns Hopkins reporting 862. I believe the JH number is more correct for this one particular statistic. Most countries that have been dealing with the pandemic longer than we have already have many more recoveries than deaths. In China, for instance, the resolved cases are about 90% recoveries and 4% deaths. That leaves around 6% that are still considered active cases.

  3. Is there some way to compare reported cases vs population with completed tests vs. population?

    It seems to me that is the biggest hole in the data. As it is, the less testing we do, the better we are able to deny, deny, deny.

    1. I have not found reliable statistics on numbers of people tested -- under-reporting, double-reporting are both problems. Fewer tests do lead to lower positive numbers (which looks good). They will also lead to higher deaths/reported cases because those not tested but positive are likely to be less serious cases (which in the end might be a much more damaging statistic, as it implies a less effective medical response).

  4. This article and the comments are so interesting. Thank you Jim.