Skip to main content

Chronic Fatigue Syndrome and Long-COVID are two conditions that share several commonalities. This article is intended to inform readers on the characteristics of these illnesses, and is not a substitute for professional medical advice, diagnosis or treatment.

What is Chronic Fatigue Syndrome (CFS)?

Chronic Fatigue Syndrome (CFS) is a condition that is primarily identified by the experience of profound tiredness irrespective of adequate bed rest. It is also known as myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS). Common symptoms include sensitivity to light, headache, tender lymph nodes, fatigue and weakness, muscle and joint pain, inability to concentrate, insomnia, forgetfulness, and depression. Sufferers of this condition may find their symptoms worsening when they engage in physical or mental activity. The onset of CFS can be sudden and may last for years. The impaired functioning of individuals with CFS leads over 50% of patients to require specialized care services. (Salari et al. 2022)

How is Chronic Fatigue Syndrome Diagnosed?

Chronic Fatigue Syndrome is characterized by at least 6 months of fatigue and burnout. (Salari et al. 2022) Precise diagnosis of Chronic Fatigue Syndrome is challenging as the disease is complex and has a controversial history. Currently, ME/CFS is diagnosed and distinguished from other illnesses by a medical exam conducted by a physician in which the patient’s health history and current symptoms are considered. The illness may differ in severity and has an unpredictable pattern of remission and relapse. The diagnosis of ME/CFS is further complicated by a lack of education about and acceptance of the illness in the medical community. Further information about the diagnostic criteria can be found at the Centers for Disease Control and Prevention website.

Recent breakthroughs in the detection of a fatigue biomarker from an individual saliva sample have made it easier for an objective measurement of fatigue to be gained. In a study by Jason, Kalns, Richarte, Katz, & Torres, it was found that severe ME/CFS in patients was significantly correlated with lower fatigue index scores, which are calculated based on the detection of the fatigue biomarker peptides. This study indicates that with further research, there may be a path forward for objective confirmation of cases of CFS. (Jason, Kalns, Richarte, Katz, & Torres 2021)

A photo of a female student with glasses struggling to concentrate on her work.Many individuals with ME/CFS struggle with cognitive impairments such as an inability to concentrate.
What is Long-COVID?

Long-COVID, or post-COVID-19 syndrome, describes a condition of persistent symptoms for an extended period following infection with COVID-19. Awareness of Long-COVID emerged in early 2020, as researchers observed that some COVID-19 patients experienced symptoms including fatigue, shortness of breath, olfactory and taste disorders, chest pain, myalgia, and sleep and mental disorders following recovery from their initial infection. These symptoms are observed to last for months and disrupt the quality of life of affected individuals. (Salari et al. 2022)

It is estimated that 10-20% of COVID-19 patients will have Long COVID symptoms within weeks or months of their recovery from the acute COVID-19 infection. Additionally, the severity of the immune-inflammatory response during the acute infection phase is known to predict the physio-affective phenome of Long COVID. A study found that health-related quality of life scores were significantly lower in individuals with Long COVID and that these findings were predicted by aspects of the immune-inflammatory response, namely neuroimmunotoxic and oxidative pathways. This is significant because oxidative stress is a phenomenon that has been linked to both Long COVID and ME/CFS. (Maes et al. 2022)

How are the two conditions related?

Fatigue is a strikingly common symptom of post-COVID-19 syndrome, with some studies showing the prevalence of fatigue to be as high as 90% in affected individuals. With the diagnostic criteria of CFS in mind, it is notable that there is a significant overlap between the manifestations of symptoms in CFS and post-COVID-19 syndrome or Long-COVID.

A study conducted in 2021 identified common biological abnormalities among patients with acute COVID-19 and ME/CFS including redox imbalance, systemic inflammation and neuroinflammation, an impaired ability to generate adenosine triphosphate, and a general hypometabolic state. These symptoms are interrelated and multidirectional. (Paul, Lemle, Komaroff, & Snyder 2021)

Post-COVID fatigue is noted to be more prevalent among women than men, with some studies indicating that it could be as much as three times more common, potentially due to hormones that cause the acute inflammatory phase to continue beyond the period necessary for the treatment of the infection. (Salari et al. 2022)

How might COVID-19 lead to CFS-like symptoms?

COVID-19 viral infection stimulates increased mitochondrial function which leads to increased reactive oxygen species (ROS) production. This mechanism is crucial to the body’s effective immune response, but when levels of ROS remain elevated, the result is a continuous cycle of inflammation and mitochondrial dysfunction. Inflammation, particularly neuroinflammation, is known to be responsible for the fatigue and cognitive deficits that individuals with ME/CFS experience. (Paul, Lemle, Komaroff, & Snyder 2021)

A photo of a woman with braids wearing a face mask outdoors for protection against COVID-19. A common feature of post-COVID-19 syndrome, or Long-COVID, is fatigue, with up to 90% of patients reporting this symptom.


Why is diagnosing and treating Chronic Fatigue Syndrome a complex process?

Myalgic encephalomyelitis or Chronic Fatigue Syndrome refers to a collection of symptoms such as fatigue, post-exertional malaise, sleep disturbances, cognitive impairment, and non-provoked pain that persist for more than 6 months with substantial intensity and not completely explained by any existing medical condition. These symptoms range widely and their etiology involves immune, virologic, psychological, endocrine, and other factors. (CDC)

There currently is no official test for ME/CFS, but research in this area is promising. Fatigue biomarker testing is an emerging area of objective measurement of fatigue that can help evaluate how neurological and immunological characteristics of CFS patients differ from those of healthy individuals. As mentioned previously, the symptoms and severity of this condition can vary vastly across individuals, but the identification of biomarkers of fatigue represents an exciting path toward establishing subtypes of the condition and developing personalized treatment procedures to improve the quality of life for those who are affected. (Fischer et al. 2013)

Chronic Fatigue Syndrome research has faced pushback in the medical and scientific community from those who deny the existence or severity of the condition, though in recent years more funding for research has been available. The lack of understanding of ME/CFS etiology underlies both the need for further research and the reluctance to affirm its credibility. Individuals who suffer from ME/CFS are highly likely to experience adverse psychosocial effects and loneliness, which are only compounded by widespread ignorance regarding their condition. (Boulazreg and Rokach, 2020)

What organizations are researching Chronic Fatigue Syndrome and Long COVID?

  • The Solve ME/CFS initiative: This nonprofit organization partners with medical organizations and government agencies to advocate for the research and treatment of ME/CFS and other long-haul diseases such as Long COVID. Solve M.E. funds research through their Ramsay Research Grant Program, and since the program was established in 2016, they have supported 34 studies involving a network of 91 research collaborators. Their You and M.E. registry contains patient-reported data and biological samples to support the fight against ME/CFS and Long COVID.
  • The Open Medicine Foundation’s End ME/CFS Project: The Open Medicine Foundation’s network of seven Collaborative Research Centers is dedicated to diagnosing, treating, and finding a cure for diseases such as ME/CFS. Since the establishment of the foundation in 2012, they have raised over $40 million to fund research and treatment of multi-system chronic, complex diseases (msCCD). Their participant registry, StudyME, is a research tool for connecting researchers and participants to further research on ME/CFS, Long COVID, Fibromyalgia and other post-infection illnesses.
  • The Bateman Horne Center: The BHC seeks to advance the diagnosis and treatment of ME/CFS, fibromyalgia, and other post-viral syndromes through research, education, and informed clinical care. This organization, described as a Center of Excellence, partners with other research institutions and non-profits to improve the lives of those who suffer from these illnesses. 
  • Other research networks include MECFSnet and IACFS/ME.
Last year, Solve M.E. launched the first nationwide Long COVID PSA campaign to spread awareness about the debilitating symptoms of the condition and the urgent need for research.


What other resources exist for those affected by Chronic Fatigue Syndrome and Long COVID?

  • Several of the organizations listed above have pages for those who seek educational resources and support.
  • Phoenix Rising: This ME/CFS Community Forum is a valuable resource for individuals seeking answers to questions about their condition or community with those who may understand their struggles.
If you believe that you may be experiencing symptoms of ME/CFS or Long COVID, seek medical care. Remember, you are not alone.

Leave a Reply