Exploration of Intersections and Divergences of Long COVID and Chronic Fatigue Syndrome.
Kouyoumdjian, Joao A, Yamamoto, Leticia A, Graca, Carla R · Cureus · 2025 · DOI
Quick Summary
This study looked at how Long COVID and ME/CFS might be related by comparing people with Long COVID symptoms to those without and healthy controls. While many Long COVID patients experienced symptoms that overlap with ME/CFS—like post-exertional malaise (feeling worse after activity), brain fog, and sleep problems—only about 1 in 5 Long COVID patients actually met the official diagnostic criteria for ME/CFS. The findings suggest that Long COVID and ME/CFS are related but distinct conditions.
Why It Matters
Understanding whether Long COVID and ME/CFS are the same condition or related-but-different diseases is crucial for developing appropriate treatments and diagnostic approaches. This study helps clarify that while Long COVID and ME/CFS share many symptoms, they may represent distinct conditions or disease subtypes, which could guide future research and clinical management strategies.
Observed Findings
All 19 LC-yes participants (100%) reported post-exertional malaise, compared to significantly lower rates in LC-no and control groups
ME/CFS was diagnosed in 18.8% of LC-yes cases, 6.7% of LC-no cases, and 10.8% of control subjects, with no statistically significant differences between groups
Experiencing six or more symptoms during acute SARS-CoV-2 infection was associated with a twofold higher risk of developing Long COVID
LC-yes individuals showed significantly higher rates of neurosensory disturbances, cognitive impairment, sleep disturbances, and pain compared to LC-no and control groups
Inferred Conclusions
Many Long COVID symptoms overlap with ME/CFS, but the majority of Long COVID cases do not meet established ME/CFS diagnostic criteria
Long COVID and ME/CFS appear to be related but distinct conditions rather than identical diagnoses
Acute infection symptom burden may be a risk factor for developing Long COVID, independent of whether ME/CFS criteria are met
While post-exertional malaise is nearly universal in Long COVID, it alone does not reliably distinguish LC from other conditions or predict ME/CFS diagnosis
Remaining Questions
What biological or immunological mechanisms explain why some Long COVID patients meet ME/CFS criteria while most do not?
What This Study Does Not Prove
This small cross-sectional study cannot establish causality or determine whether Long COVID causes ME/CFS or whether they share common underlying mechanisms. The relatively low prevalence of ME/CFS diagnosis in all groups means the findings may not generalize to larger, more diverse populations, and the lack of significant differences in ME/CFS prevalence across groups limits conclusions about specific associations between Long COVID status and ME/CFS diagnosis.