Wallraven, Timon, Günthner, Roman, Lethen, Isabelle et al. · BMC medicine · 2026 · DOI
Researchers studied blood vessel changes in the tiny vessels of the eye (using a technique called retinal vessel analysis) in people with post-COVID-19 syndrome and a subgroup meeting ME/CFS criteria, compared to people who recovered from COVID-19 and those never infected. People with post-COVID-19 syndrome, particularly those meeting ME/CFS criteria, showed narrower arteries and altered vessel patterns associated with worse symptoms and higher inflammation markers. While these findings are reported as preliminary observations, the relevance of post-COVID-19 vessel changes to ME/CFS specifically remains unclear, and this study does not yet establish whether such changes cause symptoms or could guide treatment.
By analogy to post-COVID-19 syndrome, this study suggests microvascular and endothelial alterations may be observable features associated with ME/CFS in a subset of patients. The finding that ME/CFS patients showed the most pronounced retinal vessel changes and that these changes correlated with symptom severity raises the possibility that microvascular assessment could eventually serve as an objective marker for disease monitoring, though clinical utility for ME/CFS patients specifically has not yet been established. The link between microvascular changes and inflammatory markers observed in PCS/ME/CFS may inform understanding of potential biological pathways, though whether these represent mechanism or biomarker remains undetermined.
This case-control study does not establish causation; the observed microvascular alterations may reflect consequences of infection rather than drivers of persistent symptoms. The study does not confirm that microvascular changes directly cause PEM or other ME/CFS symptoms. Findings are from a post-COVID-19 cohort, and direct extrapolation to the broader ME/CFS population (which includes non-viral-onset and long-standing cases) is not warranted without replication. RVA does not measure symptom severity itself—only a correlation is reported. This study does not constitute a treatment recommendation or diagnostic validation.
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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Primary citation
Wallraven, Timon, Günthner, Roman, Lethen, Isabelle, Ribeiro, Andrea, Lech, Maciej, Oertel, Frederike Cosima, et al. (2026). Microvascular remodeling and endothelial dysfunction across the post-COVID-19 spectrum: a prospective observational case-control study.. BMC medicine. https://doi.org/10.1186/s12916-026-05144-9
BibTeX
@article{mecfsatlas-wallraven-2026-microvascular-remodeling,
author = {Wallraven, Timon and Günthner, Roman and Lethen, Isabelle and Ribeiro, Andrea and Lech, Maciej and Oertel, Frederike Cosima and Reeß, Lukas Gabriel and Haller, Bernhard and Streese, Lukas and Hanssen, Henner and Basta-Wunderle, Michael and Schmaderer, Christoph},
title = {Microvascular remodeling and endothelial dysfunction across the post-COVID-19 spectrum: a prospective observational case-control study.},
journal = {BMC medicine},
year = {2026},
doi = {10.1186/s12916-026-05144-9},
note = {PubMed: 42625188},
url = {https://www.mecfsatlas.com/evidence/wallraven-2026-microvascular-remodeling},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-08-22. https://www.mecfsatlas.com/evidence/wallraven-2026-microvascular-remodeling
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