I wrote this for my Substack. Posting it here as I hope that I am wrong, and I'm looking for people to debunk my arguments. I found this post and this post, but both are old and contain numerous factual errors (I don't think they were wrong at the time of writing, but better data has come out since they were written. The point of this post isn't to debunk them directly, and I can obviously expand if requested, but for example, we now know that long COVID in children appears quite common).

Imagine a world where hundreds of millions of people are too sick to work. Could society continue to function?

It may sound hyperbolic, but barring some incredible fortune¹, it looks like that’s where we are headed: A decade from now, almost one third of the world’s population could suffer from a severe chronic illness — the consequence of repeated COVID infections.

This condition, known as long COVID or post-COVID, isn’t rare. It affects many people who catch COVID. Even if they caught COVID before. Even if they are young and healthy. Even if they are vaccinated (or not vaccinated).

There are still a lot of unknowns, but the story that’s emerging goes like this:

• Given that COVID is highly contagious, and immunity short-lasting, every person on the planet will probably catch COVID many times over their course of their life.
• Every time a person catches COVID, there’s a chance they will develop long COVID. So with each reinfection, the cumulative probability of developing long COVID increases.
• All people with long COVID suffer from a reduction in their quality of life, but some are worse than others. Many people with long COVID are too disabled to work.
• Some people recover from long COVID, but for others it may be lifelong. And even when people do recover, a COVID reinfection often triggers a relapse back into long COVID. Reinfections can also make existing long COVID more severe.

Over time, as people rack up more and more COVID reinfections, the total number of people suffering from long COVID will increase. Some of these people will be too sick to hold a job. More and more people will be forced to turn to government disability programs. The labor force will shrink. Healthcare systems, and society in general, will be tremendously strained.

What is long COVID, and what causes it?

There are famous actors (source), athletes (source), politicians (source), and entertainers (source) who have publicly struggled with long COVID.

The CDC estimates that around 15 million Americans have long COVID as of June, 2023 (source). Loss of smell and taste, extreme exhaustion after physical activity, chronic cough, and brain fog are common symptoms (source) but there are at least 196 others (source).

Long COVID may be several distinct, occasionally overlapping illnesses. In some cases, long COVID is the result of organ damage from a COVID infection: lesions on the brain (source), scarring of the lungs (source), or heart damage (source).

In other instances, symptoms may be due to a persistent, long-lasting COVID infection (source) — COVID may be hiding out in parts of the body the immune system cannot reach. COVID has been found in stool samples of people months after they seemingly recovered (source), and it has been found in the brain and spinal cord (source).

Another possibility is that long COVID is an autoimmune disease (source) like multiple sclerosis, which is thought to be caused by the Epstein-Barr virus (source). Perhaps COVID is similar.

For some, long COVID could be the result of a vaccine injury (source). But long COVID predates the existence of COVID vaccines (source), and there are studies documenting people with long COVID who were not vaccinated (source).

1. Given that COVID is highly contagious, and immunity short-lasting, every person on the planet will probably catch COVID many times over their course of their life.

About 77% of American adults and teenagers were estimated to have caught COVID at least once (source) as of the end of 2022. At this point in the pandemic, most people know someone who has had COVID multiple times.

Immunity from vaccination or an infection wanes after only a few months (source), leaving people vulnerable to reinfection again and again. In fact, there are documented cases of people getting reinfected in less than 3 weeks (source), and reports of people having been infected with COVID at least 7 times (source).

Given that COVID is now known to be among the most contagious viruses in history (source) and immunity is short-lived, some experts believe the average person may contract COVID at least once per year for the foreseeable future (source).

2. Every time a person catches COVID, there’s a chance they will develop long COVID. So with each infection, the cumulative probability of developing long COVID increases.

What are the odds of developing long COVID?

• The WHO says 1 in 10 COVID infections will result in long COVID (source).
• Researchers at UCLA say 30% of COVID patients develop long COVID (source).
• The CDC found that 20%-25% of COVID patients develop long COVID (source).
• Chinese University said that 70% of people infected with COVID in Hong Kong developed some form of long COVID (source).
• Researchers at the Imperial College of London said 1 in 3 people who had COVID have long COVID symptoms (source).

Even using the most charitable estimate, about 10% of people will develop long COVID following a COVID infection. The rest may not. And if they’ve had one or two COVID infections without issue, they make think they’re safe — but they’d be mistaken.

With reinfection, there’s some evidence that a person’s odds of developing long COVID following that particular infection may decline (source) but they do not fall to 0%. Thus, their cumulative odds of developing long COVID increase following every reinfection.

In other words, people who have had COVID twice are more likely to have long COVID than those who have only had it once. And those who have had it three times are more likely to have long COVID than those who have only had it twice (source).

"You will have many patients come to us…with maybe the third, fourth, fifth infection, and now having finally developed post-Covid symptoms" said Dr. Marc Sala in an interview with Fox (source).

It’s not clear if some COVID variants are more likely to cause long COVID than others, but more recent omicron variants, like prior strains, are known to cause long COVID (source, source).

Unfortunately, there doesn’t seem to be much a person can do to avoid long COVID if they get infected. Existing COVID vaccines do not protect from long COVID. They reduce the odds, but only marginally — about 15%, according to a study of more than 13 million people (source). Those with pre-existing health conditions and older people are more likely to develop long COVID (source, source), but healthy people are also getting long COVID in large numbers: about one third of people living with long COVID had no pre-existing health conditions (source).

Taking Paxlovid during a COVID infection appears to reduce the odds of long COVID more than vaccination, but again, it’s only marginal — a 19%-26% reduction (source). Metformin was found to be better still, with a 41% reduction (source) but not foolproof.

At this point, the only way to reliably avoid long COVID is to avoid COVID.

3. All people with long COVID suffer from a reduction in their quality of life, but some are worse than others. Many people with long COVID are too disabled to work.

Long COVID varies in severity. Some people have only smell or taste loss, while others become completely bed-bound. But even a relatively minor case of long COVID results in tangible impacts to quality of life and a significant increase in depression (source). Some people with long COVID have a lower quality of life than people with stage 4 lung cancer, and it has a bigger impact on their day-to-day activities than a stroke (source).

But at what point does this suffering have a tangible impact on society? Perhaps when people can no longer work. The data on that varies, but it’s common for people suffering from long COVID to reduce their work hours or to stop working entirely:

• A survey of patients seeking treatment at a long COVID clinic found that 20% of them couldn’t work (source).
• A report from the New York State Insurance Fund found that 18% of people receiving workers’ compensation for long COVID could not return to work for over a year (source).
• A study from the Minneapolis Fed found that 26% of people with long COVID had their work impacted — about 40% of them couldn’t work at all, and the rest worked fewer hours (source).
• The Brookings Institute estimated that 4 million Americans were out of work in 2022 because of long COVID (source).

4. Some people recover from long COVID, but for others it may be lifelong. And even when people do recover, a COVID reinfection often triggers a relapse back into long COVID. Reinfections can also make existing long COVID more severe.

Some people with long COVID do recover eventually, but it often takes years. Others have still not recovered since the pandemic began (perhaps they will at some point, but there is reason to believe they may never recover²). A study of over 31,000 people infected with COVID found that 6% of them had not recovered when the study ended 18 months later (source). A more recent study looking specifically at people with long COVID found that over 92% of them did not recover after 2 years (source).

Reinfections appear to be particularly dangerous for people living with long COVID, or those who have recovered from it. A survey of people living with long COVID found that 45% of them who were reinfected had long COVID symptoms that had previously cleared up return with reinfection; worse, 41% said reinfection brought additional long COVID symptoms. For those who had recovered from long COVID entirely, about 60% of them developed long COVID again following reinfection (source).

A decade from now, perhaps one third of the world’s population could suffer from a severe chronic illness

The probabilities are highly uncertain, but let’s settle on a few assumptions and see what the math looks like.

Let’s assume:

• Every person catches COVID, on average, once per year going forward.
• The odds of long COVID are 10% after the first infection, and 5% after every reinfection.
• The average person suffering from long COVID recovers after 2 years.
• When a person with long COVID recovers, then becomes reinfected, they have a 60% chance of developing long COVID again.
• 25% of people with long COVID work fewer hours or don’t work at all.
• There’s no cure for long COVID (currently the case).

Under these assumptions, after 10 years:

• 40% of people will have had long COVID at some point.
• 30% of people will have active long COVID.
• 7.5% of people will be so disabled from long COVID it will impact their work.

The pandemic has been ongoing for over 3 years already, but mitigation efforts were in place to some degree for 2 of those years, which may have limited the number of infections and reinfections.

If we assume that at this point, 80% of people have had COVID, and the average person who has had COVID has had it once, then the assumptions above predict that 8% of people have active long COVID, and 2% of people are so disabled by long COVID it is impacting their ability to work.

The CDC pulse survey puts the percentage of American adults suffering from long COVID at 6% and the percentage of adults where long COVID is having a significant impact on their life at 1.6% (source), so the assumptions above may be slightly too pessimistic, but not wildly so.

The best data to predict where we are headed would be from a large sample of people who have had COVID many times (10+). If most or all of these people had long COVID, then my projections may be close to the truth. Unfortunately, as testing has been scaled back (source), it may be difficult to find such people.

The evidence that is out there seems to point in that direction: a study of over 400,000 US veterans who contracted COVID showed that the more times they had been infected with COVID, the more health problems they had afterwards (source).

Long COVID will cost trillions of dollars.

In a recent paper, Harvard economist David Cutler pegged the cost of long COVID at $3.7 trillion (source). Notably, he looked only at people who are currently suffering from long COVID today (source). He assumes about 9.6 million Americans are living with severe long COVID, or about 3% of the population.

Given that people are continuing to be infected, and continuing to develop long COVID, Cutler’s projection is a gross underestimate. If my assumptions are correct, and that number doubles or triples in the years ahead, the total cost of long COVID could be in excess of $10 trillion, or almost 50% of US GDP. Of course, that is only looking at the US — long COVID affects every country on Earth.

“The oncoming burden of long COVID…is so large as to be unfathomable,” wrote a group of immunology professors in a recent analysis in Nature (source).

I disagree — although uncomfortable, the consequences of long COVID can be understood. The data is out there, and the direction we are heading in is obvious. Hopefully, once more people understand this problem, we can begin to solve it.

1Some possibilities: (1) The virus evolves in such a way that future variants no longer cause long COVID. (2) Hygienic infrastructure (e.g. air filtration, devices that detect the presence of COVID in the air) or a sterilizing vaccine is deployed at scale and it sharply reduces the number of infections. (3) Effective treatments/cures are developed for long COVID.

2It’s a different coronavirus, but SARS-CoV-1 produced a similar phenomenon to long COVID. Far fewer people were infected with SARS than with COVID, but of those that were, some of them developed “long SARS” and they have not recovered even 20 years later (source).