Haran, John P, Bradley, Evan, Zeamer, Abigail L et al. · JCI insight · 2021 · DOI
This study looked at bacteria in the mouth of people with COVID-19 to understand why some people develop long COVID. Researchers found that people with long COVID had higher levels of inflammation-causing bacteria, particularly types called Prevotella and Veillonella. Interestingly, the oral bacteria patterns in long COVID patients resembled those seen in chronic fatigue syndrome patients, suggesting the microbiome may play a role in prolonged illness.
This research provides evidence that oral microbiome dysbiosis may contribute to long COVID, a condition that shares clinical features with ME/CFS. Understanding microbial drivers of prolonged inflammation could open new diagnostic and therapeutic avenues for both long COVID and ME/CFS patients, potentially through targeted microbiome interventions.
This study demonstrates association, not causation—it does not prove that dysbiosis causes long COVID symptoms or that restoring the microbiome would resolve illness. The study also does not establish whether microbiota changes are a cause, consequence, or epiphenomenon of prolonged infection. Additionally, findings from one microbiome compartment (oral) may not reflect systemic dysbiosis.
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
Haran, John P, Bradley, Evan, Zeamer, Abigail L, Cincotta, Lindsey, Salive, Marie-Claire, Dutta, Protiva, et al. (2021). Inflammation-type dysbiosis of the oral microbiome associates with the duration of COVID-19 symptoms and long COVID.. JCI insight. https://doi.org/10.1172/jci.insight.152346
BibTeX
@article{mecfsatlas-haran-2021-inflammation-type,
author = {Haran, John P and Bradley, Evan and Zeamer, Abigail L and Cincotta, Lindsey and Salive, Marie-Claire and Dutta, Protiva and Mutaawe, Shafik and Anya, Otuwe and Meza-Segura, Mario and Moormann, Ann M and Ward, Doyle V and McCormick, Beth A and Bucci, Vanni},
title = {Inflammation-type dysbiosis of the oral microbiome associates with the duration of COVID-19 symptoms and long COVID.},
journal = {JCI insight},
year = {2021},
doi = {10.1172/jci.insight.152346},
note = {PubMed: 34403368},
url = {https://www.mecfsatlas.com/evidence/haran-2021-inflammation-type},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-28. https://www.mecfsatlas.com/evidence/haran-2021-inflammation-type
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