Xu, Wangzi, Cao, Yu, Wu, Lin · International journal of environmental research and public health · 2023 · DOI
This study investigated whether COVID-19 infection actually causes ME/CFS or if the illnesses just happen to occur together. Researchers analyzed genetic data from thousands of people to look for a direct causal link between COVID-19 and ME/CFS. They found no significant connection, suggesting that while some people may develop ME/CFS-like symptoms after COVID-19, the virus itself may not be a direct cause of ME/CFS.
This study addresses a clinically important question about whether COVID-19 is a true causal trigger for ME/CFS or whether symptom overlap is coincidental. Clarifying this relationship helps healthcare providers differentiate between post-COVID conditions and ME/CFS, potentially improving diagnostic accuracy and treatment approaches. Understanding causation also informs public health strategies and research priorities.
This study does not prove that COVID-19 never precedes ME/CFS symptom onset in individual cases, nor does it address whether viral infections broadly might trigger ME/CFS in genetically susceptible people. Genetic association studies cannot exclude rare causal pathways or environmental interactions, and they do not assess temporal sequencing or clinical phenotypes in detail.
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 →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Xu, Wangzi, Cao, Yu, & Wu, Lin (2023). No Causal Effects Detected in COVID-19 and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Two Sample Mendelian Randomization Study.. International journal of environmental research and public health. https://doi.org/10.3390/ijerph20032437
BibTeX
@article{mecfsatlas-xu-2023-causal-effects,
author = {Xu, Wangzi and Cao, Yu and Wu, Lin},
title = {No Causal Effects Detected in COVID-19 and Myalgic Encephalomyelitis/Chronic Fatigue Syndrome: A Two Sample Mendelian Randomization Study.},
journal = {International journal of environmental research and public health},
year = {2023},
doi = {10.3390/ijerph20032437},
note = {PubMed: 36767803},
url = {https://www.mecfsatlas.com/evidence/xu-2023-causal-effects},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/xu-2023-causal-effects
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