Summary
| Direction in Long COVID | ↓ Reduced — lower than in the comparison group |
|---|---|
| Category | Microbiome |
| Also described as | Shannon index |
| Compared against | HC (healthy controls) |
| Associated symptoms | GI symptoms, dysbiosis |
| Test type | Blood test (serum / plasma / whole blood) |
| Source | Baalbaki et al. 2025 — doi:10.1111/all.16526 |
| Condition atlas | Long COVID Biomarker Atlas |
Trials, interventions and tests
In clinical-trial registrations this marker maps to the outcome term Change in gut microbiota diversity and richness (1 registered trials use a matching outcome measure).
Clinical trials using Gut microbiome alpha diversity as an outcome
- NCT05556733: FMT for Post-acute COVID-19 Syndrome (Unknown)
Outcome measure: Change in gut microbiota diversity and richness
Related Microbiome markers in Long COVID
Full list: Long COVID Biomarker Atlas.
Frequently asked questions
Is Gut microbiome alpha diversity high or low in Long COVID?
Reduced. Studies summarised in the OSMF atlas report lower Gut microbiome alpha diversity in Long COVID than in healthy controls. Source: Baalbaki et al. 2025.
What symptoms is Gut microbiome alpha diversity associated with in Long COVID?
The cited literature associates this marker with GI symptoms, dysbiosis. These are population-level associations and do not mean the marker causes the symptoms.
Which test measures Gut microbiome alpha diversity?
It is measured as a blood test (serum / plasma / whole blood). Many of the cited studies used research-grade assays, so clinical availability may vary.
Is one abnormal Gut microbiome alpha diversity result diagnostic of Long COVID?
No. No single biomarker is diagnostic of Long COVID. Gut microbiome alpha diversity findings come from group comparisons, overlap considerably between patients and controls, and vary with study design, timing and comparison group. A result should be interpreted by a clinician alongside symptoms, history and other tests.
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Last reviewed: 2026-06-29 · Page generated from long-covid.json · Browse: Long COVID atlas · Biomarker Index · All marker pages
Disclaimer: This page is an educational synthesis of published, peer-reviewed research and is not medical advice. Biomarker findings vary across studies with case definitions, comparison groups, timing and assay methods. Direction of change reflects the predominant finding in the cited source and does not establish a diagnostic threshold. Discuss any test result with a qualified clinician.