Tens of thousands of people in the United States have lingering illness following COVID-19. In the US, we call them post-COVID “long haulers.” Currently, the condition they are suffering from is known as “long COVID,” although other names are being proposed.

Suppose you are suddenly are stricken with COVID-19. You become very ill for several weeks. On awakening every morning, you wonder if this day might be your last.

And then you begin to turn the corner. Every day your worst symptoms — the fever, the terrible cough, the breathlessness — get a little better. You are winning, beating a life-threatening disease, and you no longer wonder if each day might be your last. In another week or two, you’ll be your old self.

But weeks pass, and while the worst symptoms are gone, you’re not your old self — not even close. You can’t meet your responsibilities at home or at work: no energy. Even routine physical exertion, like vacuuming, leaves you feeling exhausted. You ache all over. You’re having trouble concentrating on anything, even watching TV; you’re unusually forgetful; you stumble over simple calculations. Your brain feels like it’s in a fog.

Your doctor congratulates you: the virus can no longer be detected in your body. That means you should be feeling fine. But you’re not feeling fine.

The doctor suggests that maybe the terrible experience of being ill with COVID-19 has left you a little depressed, or experiencing a little PTSD. Maybe some psychiatric treatment would help, since there’s nothing wrong with you physically. You try the treatment, and it doesn’t help.

Published studies (see here and here) and surveys conducted by patient groups indicate that 50% to 80% of patients continue to have bothersome symptoms three months after the onset of COVID-19 — even after tests no longer detect virus in their body.

Which lingering symptoms are common?

The most common symptoms are fatigue, body aches, shortness of breath, difficulty concentrating, inability to exercise, headache, and difficulty sleeping. Since COVID-19 is a new disease that first appeared in December 2019, we have no information on long-term recovery rates.

Moving toward a better definition of long haulers –– and a new name

Very different chronic illnesses may develop in some people who have had COVID-19. So, the National Institutes of Health (NIH) has proposed a unifying name: post-acute sequelae of SARS-CoV-2 infection, or PASC. (SARS-CoV-2 is the virus that causes COVID-19.)   

Most people who get COVID-19 recover within weeks or a few months. However, some will likely suffer chronic damage to their lungs, heart, kidneys or brain that the virus inflicted. Others will develop long COVID.

We do not yet have a formal definition of long COVID. In my opinion, such a definition should include these three points:

• A medical diagnosis of COVID-19, based on both symptoms and/or diagnostic testing for the SARS-CoV-2 coronavirus
• Not having returned to pre-COVID-19 level of health and function after six months
• Having symptoms that suggest long COVID, but no evidence of permanent damage to the lungs, heart, and kidneys that could cause those symptoms.

Is long COVID the same as chronic fatigue syndrome (ME/CFS)?

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has speculated that long COVID likely is the same as or very similar to myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).

ME/CFS can be triggered by other infectious illnesses — such as mononucleosis, Lyme disease, or severe acute respiratory syndrome (SARS), another coronavirus disease. Before the pandemic, the National Academy of Medicine estimated that as many as 2.5 million people in the US are living with ME/CFS. I recently published an article in the journal Frontiers in Medicine  indicating that the pandemic could well double that number in the next year.

Who is more likely to become a long hauler?

Currently, we can’t accurately predict who will become a long hauler. As an article in Science notes, people only mildly affected by COVID-19 still can have lingering symptoms, and people who were severely ill can be back to normal two months later.

However, continued symptoms are more likely to occur in people over age 50, people with two or three chronic illnesses, and, possibly, people who became very ill with COVID-19.

What might cause the symptoms that plague long haulers?

Research is underway to test several theories. People who have ME/CFS, and possibly people with long COVID, may have one or more of these abnormalities:

• an ongoing low level of inflammation in the brain;
• an autoimmune condition in which the body makes antibodies that attack the brain;
• decreased blood flow to the brain, due to abnormalities of the autonomic nervous system;
• difficulty making enough energy molecules to satisfy the needs of the brain and body.

The bottom line

How many people may develop long COVID? We can only guess. By late February, 2021, almost 30 million Americans were confirmed to have been infected by the virus. Probably many more were never diagnosed. Early studies indicate that one in ten people with COVID-19 may develop long COVID that lasts at least a year. Ultimately, how long these illnesses last remains to be determined.

For this and many other reasons, the strain on the American health care system and economy from the pandemic will not end soon. Fortunately, the NIH and CDC have committed major support for research on long COVID. In the US and around the world, planning is underway to develop centers dedicated to research into long COVID and caring for those who have it.

Virtually every health professional I know believes that the pandemic in the US could and should have been better controlled than it has been. Bad mistakes rarely lead to only temporary damage.