Jason, Leonard A, Dorri, Joseph A · Neurology international · 2022 · DOI
Researchers studied 465 people with long-term COVID symptoms to see how many also had ME/CFS (a serious condition causing extreme fatigue and worsening after activity). They found that about 6 in 10 people with long COVID met the medical criteria for ME/CFS. Interestingly, some people thought they had ME/CFS when they didn't, while others had ME/CFS without realizing it—showing that self-diagnosis alone isn't reliable.
This study quantifies the substantial overlap between Long COVID and ME/CFS, challenging the assumption that Long COVID and ME/CFS are entirely separate conditions. It demonstrates that objective diagnostic criteria are essential because patient self-report alone misses or over-identifies ME/CFS, which has implications for clinical recognition, patient support, and research stratification.
This study does not prove that Long COVID causes ME/CFS or establish the mechanistic relationship between them—it only documents their co-occurrence at one time point. The cross-sectional design cannot determine whether ME/CFS develops during Long COVID or represents a pre-existing condition, nor does it clarify whether they share identical biological pathways.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
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