Understanding the Links Between Long-COVID and ME/CFS
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Chapter 1: Overview of ME/CFS
Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) remains poorly understood, with significant gaps in our knowledge.
Over the 20th century, approximately 70 unexplained outbreaks of ME/CFS were documented. A notable event occurred in 1955 at the Royal Free Hospital in the UK, where 255 healthcare workers were hospitalized under mysterious circumstances. This incident prompted Dr. Melvin Ramsay to introduce the term ME, which the World Health Organization (WHO) officially recognized as a medical condition by 1969. By the early 2000s, ME was often considered synonymous with chronic fatigue syndrome (CFS), leading to the combined term ME/CFS.
Viral infections are a frequent trigger for ME/CFS, and COVID-19 stands out as a significant concern. Despite a survival rate of around 98% for COVID-19, estimates suggest that between 10-30% of those infected may experience Long-COVID, a persistent post-viral syndrome lasting 6 to 9 months. Intriguingly, the severity of the initial COVID-19 illness does not necessarily predict the development of Long-COVID; even individuals with mild cases may suffer long-term effects.
In May 2020, Long-COVID began to receive attention from social support groups and eventually from medical experts, who speculated that it could lead to ME/CFS. Nearly ten months later, some cases of Long-COVID have indeed been diagnosed as ME/CFS, but does this insight provide any real solutions?
Section 1.1: ME/CFS Diagnostic Criteria
Various diagnostic criteria for ME/CFS exist, but only three are widely recognized:
- 1994 CDC Criteria: Severe fatigue lasting at least six months, with at least four of the following symptoms: cognitive issues, swollen lymph nodes, sore throat, muscle pain, joint pain, post-exertional malaise, unrefreshing sleep, and headaches.
- 2003 Canadian Consensus Criteria: Fatigue, post-exertional malaise, sleep disturbances, muscle or joint pain, and cognitive impairment lasting six months or longer.
- 2015 IOM Criteria: Severe fatigue not alleviated by rest, post-exertional malaise, unrefreshing sleep, and either cognitive dysfunction or orthostatic intolerance persisting for six months or more.
These symptoms overlap significantly with those reported in Long-COVID, suggesting that it could already qualify as ME/CFS based on symptom duration and similarity. Diagnosis relies solely on symptom evaluation, which is inherently subjective and can lead to misdiagnosis. Currently, there are no definitive laboratory tests or biomarkers to confirm ME/CFS.
Section 1.2: Evidence of ME/CFS in Long-COVID Patients
Most research on Long-COVID has involved follow-up periods of less than six months. Among the few studies with longer follow-ups, only a small number have actively sought ME/CFS diagnoses.
Study 1:
A recent study in the Journal of Neurovirology examined 120 COVID-19 survivors who had been discharged from the hospital six months earlier. Most participants were middle-aged and had experienced mild to moderate COVID-19. Among these survivors, 21 reported fatigue, and 3 (14.3%) met the 1994 CDC criteria for ME/CFS. Additionally, 7 (5.8%) were diagnosed with PTSD.
Study 2:
Research from University College London involved 3,762 COVID-19 survivors across 56 countries, where only 8.4% had been hospitalized. At 6-7 months post-symptom onset, 77.7% reported ongoing fatigue, while 55.4% experienced cognitive impairment. Among those who sought medical diagnoses, 10.3% were diagnosed with ME/CFS following the 2015 IOM criteria.
Study 3:
A preprint study from the Berlin Institute of Health involved 42 COVID-19 survivors with moderate to severe fatigue lasting over six months. Of these, 45% met the 2003 Canadian Consensus Criteria for ME/CFS.
These findings indicate that between 10-45% of Long-COVID patients may meet ME/CFS criteria, suggesting a potential link between the two conditions.
Chapter 2: The Unknowns Surrounding ME/CFS
The first video discusses the immunological signatures between Long-COVID and ME/CFS. It sheds light on potential overlaps and implications for understanding these conditions.
In a four-year follow-up of SARS survivors, 40% reported persistent fatigue, and 27% met the 1994 CDC criteria for ME/CFS, irrespective of the initial severity of their illness. Similarly, a long-term study on 71 SARS survivors revealed that a subset continued to show signs of fatigue and other health issues over 15 years later.
The biological underpinnings of ME/CFS remain elusive. Various hypotheses have been proposed, including autoimmunity, chronic inflammation, and neuroinflammation, yet none have been definitively established. The interconnectedness of biological systems suggests that multiple factors may contribute to the disease.
Risk factors for ME/CFS include viral infections, trauma, and environmental factors, but no specific triggers have been identified. Genetic predispositions also appear relevant, as familial patterns are observed, but no conclusive genes have been linked to the condition.
Section 2.1: Treatment Approaches
Currently, effective treatments for ME/CFS are lacking. The absence of a clear biological cause complicates the development of targeted therapies. Clinical trials have yielded minimal success, with only a few demonstrating any beneficial effects.
Non-pharmacological approaches, such as cognitive-behavioral therapy (CBT) and graded exercise therapy (GET), show some promise, but neither offers a cure and their effectiveness varies among individuals. Recent critiques suggest that these treatments may even cause harm, highlighting the need for a reassessment of current recommendations.
Section 2.2: The Need for Research Funding
Despite the longstanding recognition of ME/CFS, research remains severely underfunded. In 2019, the NIH allocated merely $15 million for ME/CFS research, in stark contrast to funding levels for other conditions with established treatments.
Patient advocacy groups are working to raise awareness and support for research, yet interest from pharmaceutical companies remains low.
In summary, while some Long-COVID cases may align with ME/CFS diagnoses, our understanding of both conditions is still limited. As we move forward, addressing the gaps in research and treatment will be crucial to support the growing number of affected individuals.
The second video explores the connection between ME/CFS and Long-COVID, providing insights into the ongoing investigations in this area.