The Doubling Problem

Robert Epstein
7 min readMar 26, 2020


Both the number of cases and the number of deaths from the Covid-19 virus are currently doubling worldwide every six days. In some areas of the U.S., the doubling is occurring even faster. Unless drastic measures are taken immediately, the doubling could spell disaster for humanity.

by Robert Epstein, Ph.D.

At a press conference on March 23rd, Louisiana Governor John Bel Edwards announced that the number of new cases of coronavirus in his state had increased by a factor of 10 during the previous seven days.

If that growth rate continued, he said, Louisiana’s hospital system would be overwhelmed in 10 more days. When medical services are overrun, as they were in Italy weeks ago, medical care is rationed, many medical personnel get sick or die, larger and larger numbers of people are left untreated, and the disease spreads even faster than before.

But don’t panic — at least not until you read further. It’s possible that the Louisiana numbers were exploding simply because lots more people were being tested. Does increased testing account for the dramatic increase we are currently seeing in the number of Covid-19 cases worldwide?

Unfortunately not.

Even when you take increased testing into account, both the number of new cases of the disease and the number of deaths caused by the disease, appear to be doubling every six days.

If I had written this essay just three days ago, the doubling rate would have been every seven days, so the doubling rate appears to be increasing.

If you blame all the scary numbers we’re seeing entirely on the fact that most people haven’t been tested, you’re not thinking clearly. If the number of deaths from the virus is doubling every six days (and it is), how could that doubling be an artifact of increased testing? Anyway, if you’ve tested very few people, you’re allowing an enormous number of contagious people to roam around, and that will soon increase both the rate of diagnosed cases and the fatality rate — more on that issue in a moment.

Here, through March 25th, is a graph prepared from data being collected daily by the European CDC showing the cumulative number of Covid-19-related deaths worldwide since January 21st:

Notice how smooth the right half of that curve is (from about February 25th on) and how its angle of ascent is getting steeper. Having been a researcher for nearly four decades and having taught statistics at the doctoral level, the shape of this curve troubles me deeply. It’s telling me that efforts to flatten the curve are not only failing — they’re failing miserably. What happens if this trend continues?

In some countries, the number of cases and deaths is increasing at an even faster rate than the worldwide average. In the U.S., the number of deaths is currently doubling every three days. In Louisiana, the doubling appears to be occurring every other day.

In China and South Korea, where draconian methods were implemented almost immediately two months ago to slow the spread of the disease — massive testing, strict quarantines, a complete shutdown of public venues, severe penalties for violations, and so on — the rate of doubling is much slower than the worldwide rate. In South Korea, doubling now occurs only every 13 days; in China, if the reports we have are accurate, it appears that the disease is no longer spreading, although people who are infected are still dying.

Why is this doubling occurring, and why is it occurring at radically different rates in different regions?

Think rabbits — well, digital rabbits, anyway, that can grow up and reproduce very fast. If two rabbits produce four rabbits in seven days, and those four produce eight a week later, and those eight produce 16 a week later, it seems like no big deal. But if that doubling occurs for just 16 more weeks, there will be 1,048,576 rabbits in the newest generation. And if all the rabbits that preceded that generation are still alive, their total population will now be 2,097,150.

Diseases can spread even more quickly than rabbits can reproduce, because one ill person can infect many others. With most common illnesses, such as the cold and influenza, people often show symptoms within hours of being infected, at which they point often self-isolate, meaning they head home and go to bed.

Now and then, unfortunately, a disease appears that is contagious long before people realize they are sick. That means they are a danger to the community while still asymptomatic. Typhoid Mary and other so-called “healthy carriers” of typhoid fever unknowingly spread typhoid to thousands of Americans in the early 1900s. Typhoid Mary herself spent decades in forced isolation on a little island in the middle of New York City’s East River because of the danger she posed to the community, and when, now and then, she was allowed to reenter society, she infected more people.

Covid-19 is, alas, asymptomatic for about five days, during which carriers are highly contagious. In other words, around the world right now, many thousands of people have been infected by the virus and don’t know it, and while they’re out and about, they’re spreading the virus to other people who, in turn, will spread the virus to others.

That’s why the virus is spreading so fast, and that’s also why the rate at which is spreading is increasing.

In some regions, the virus is spreading more slowly because of three things: drastic restrictions on in-person social interactions, contact tracing, and massive testing.

Although our leaders have been telling us for weeks now that millions of Covid-19 test kits are available and that everyone who wants a test can get one, the sad truth is that there is still an extreme shortage of test kits in the U.S. As a result, only a small portion of people who are actually sick are being tested, and no one who is asymptomatic is being tested.

In other words, we are rapidly surrounding ourselves with tens of thousands of Typhoid Marys.

In one of the most promising coronavirus studies conducted so far, researchers at the University of Padua in Italy tested all 3,300 residents of a small Italian town called Vò, and all 90 people who tested positive — some symptomatic, some not — were immediately isolated. This instantly stopped transmission of the virus. The researchers concluded that if you really want to stop the virus from spreading, the solution is “testing, testing, testing.”

The ultimate expression of this idea would be to test everyone, everywhere, and then to separate the people who are infected from those who are not. As I explain in a new essay, this idea is not only feasible, it’s much cheaper than the haphazard and largely ineffective bandaids that are being applied to the coronavirus problem at the moment. Universal Testing will quickly kill the virus and allow our economies to start up again almost immediately.

The doubling problem is especially serious when it comes to Covid-19, not only because of asymptomatic transmission but because its fatality rate currently appears to be between 10 and 34 times that of the flu. Even in Vò, where everyone was tested, three people have died so far, which gives us a fatality rate of 3.3 percent — about 33 times that of the flu. For influenza, we also have both vaccines and antiviral treatments; for the coronavirus, we have nothing.

Recent computational modelling performed by researchers at University College London suggests that if we did nothing at all to fight the spread of coronavirus in the U.S., 2.2 million Americans would die from it in a few months. Two million might seem like a crazy number, but that’s what doubling does (think rabbits).

In the U.S., we recently crossed an ominous threshold: On March 23rd, more than 100 Americans died from Covid-19. Just two days later, on March 26th, more than 200 Americans died. Unless drastic measures are taken, a few days from now, that number might exceed 400, then 800, 1,600, 3,200, and so on. Because the new coronavirus is, well, new, no one knows for sure what the actual growth rate will be, but so far the numbers look grim.

I hate to be the bearer of bad news, but if our federal government doesn’t get its act together quickly — and I see no sign of this happening at the moment — we’re in for a world of hurt.


Dr. Epstein, a former editor-in-chief of Psychology Today, is senior research psychologist at the American Institute for Behavioral Research and Technology. The author of 15 books and more than 300 articles, he is working on a book called “How Google and Facebook Ate Your Brain, and How You Can Get a New One.” Follow him on Twitter: @DrREpstein. To read his new essay, “How to Stop the Virus Now,” visit



Robert Epstein

Senior Research Psychologist at the American Institute for Behavioral Research and Technology