What Is the Link Between Long COVID and Chronic Fatigue Syndrome?
Key takeaways:
Long COVID occurs when people who’ve had COVID-19 continue to have symptoms 4 or more weeks after the infection. Fatigue is a common symptom of long COVID.
Researchers have noticed that long COVID resembles a condition called chronic fatigue syndrome. The cause of both conditions is still unclear.
People with COVID are four times more likely to have chronic fatigue after their infection.
Table of contents
A growing number of people who have recovered from acute COVID-19 go on to experience long-term symptoms, or long COVID. Experts are still trying to understand this condition. Some think it may be connected to chronic fatigue syndrome, another condition that’s been around for decades.
What is long COVID?
Some people who had COVID continue to have symptoms 4 or more weeks after their initial COVID illness. This is known as long COVID. Studies suggest that this affects about 1 in 10 people after infection. These numbers may be underreported, and the actual percentages may be much higher.
Long COVID symptoms
People with long COVID report experiencing many different symptoms. Fatigue is one of the most common symptoms. In fact, 85% of people with long COVID have fatigue. Some of the other common symptoms include:
Fatigue and tiredness, especially after activity
Shortness of breath or chest heaviness and tightness
Cough
Difficulty concentrating or focusing on tasks, sometimes called “brain fog”
Headaches
Problems sleeping
Muscle or joint pain
Heart palpitations
Nausea, vomiting, or diarrhea
Changes in taste or smell
Changes in mood
Some people have reported symptoms months after they recovered from their initial infection. Older adults and people who have a more severe infection are at greater risk of long COVID. But young people with mild or even asymptomatic illness can also experience this condition.
Scientists have only studied long COVID for a short period of time. But they’ve seen similarities with chronic fatigue syndrome.
What is chronic fatigue syndrome?
Chronic fatigue syndrome (CFS), also known as myalgic encephalomyelitis (ME), is a long-term condition that affects many systems in the body. It was first recognized in 1988. As the name suggests, it leads to debilitating fatigue that’s often worse after activity.
One report estimates that up to 2.5 million people in the U.S. have ME/CFS. And the condition is likely underdiagnosed.
Chronic fatigue syndrome symptoms
There are no specific tests to diagnose this condition. Healthcare professionals consider ME/CFS when someone experiences profound fatigue for more than 6 months with no other explanation.
People with ME/CFS are unable to do their usual activities, and some may not be able to leave bed. Symptoms may get worse with activity, a symptom called post-exertional malaise.
Other common symptoms of ME/CFS include:
Problems sleeping
Difficulty concentrating
Worsening symptoms with standing or sitting upright (orthostatic intolerance)
Headaches
Muscle and joint pain
Shortness of breath
Heart palpitations
Nausea, vomiting, or diarrhea
Recurring sore throat
If these symptoms sound familiar, it’s because many of them overlap with the symptoms of long COVID.
What is the link between long COVID and chronic fatigue syndrome?
Long COVID and chronic fatigue syndrome share a lot in common. And this has led researchers to look into a possible link. In one study, people were found to be more than four times more likely to have a diagnosis of chronic fatigue in the 18 months after having COVID. And this includes people who also had a more specific diagnosis of ME/CFS.
While it’s still early, researchers think that long COVID and ME/CFS share similar causes. Viral infection seems to cause both conditions, and they may be the result of ongoing immune system dysfunction. Similar to how COVID triggers long COVID, evidence suggests that ME/CFS may start with previous infection with a virus, such as Epstein-Barr virus.
But even after these infections are gone, researchers have found evidence that both ME/CFS and long COVID are associated with ongoing activation of the immune system. This may explain why people with these conditions experience symptoms that may resemble autoimmune disease.
How do long COVID and chronic fatigue syndrome affect the immune system?
Experts are not sure how long COVID and chronic fatigue syndrome affect the immune system. But it may be related to abnormally high cytokines (immune system markers) in both conditions. Studies suggest these cytokines play a role in the development of both ME/CFS and long COVID.
Scientists are still trying to understand why this immune system response causes such profound fatigue. One study of people hospitalized for infection found that increased inflammation from the virus caused significant muscle weakness. This inflammation caused similar weakness experienced by people with ME/CFS.
The bottom line
People with COVID are much more likely to develop symptoms of chronic fatigue. Experts aren’t entirely sure why, but long COVID and chronic fatigue syndrome (CFS) may be related. They’re both linked to viral infections and cause similar symptoms. Researchers are still trying to understand exactly why these conditions develop and if it could be related to how the immune system responds to infection.
What researchers have learned about CFS may help them understand more about why long COVID occurs. And that may lead to better insight into what treatment and recovery for these conditions may look like.
Why trust our experts?
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