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SARS-CoV-2 spike protein in Long COVID

SARS-CoV-2 spike protein, also described as Circulating spike antigen, is a viral marker with mixed findings in Long COVID (PASC, Post-Acute Sequelae of COVID-19): studies comparing patients with healthy controls report both increases and decreases. Symptom domains tied to this marker in the source include antigen persistence hypothesis. The finding is drawn from Thomas et al. 2024; it describes group-level differences, not a threshold that classifies an individual.

↕ InconsistentViral

Summary

Direction in Long COVID↕ Inconsistent — reported as both higher and lower across studies, with no consistent direction
CategoryViral
Also described asCirculating spike antigen
Compared againstHC (healthy controls)
Associated symptomsAntigen persistence hypothesis
Test typeClinical or physiological test
SourceThomas et al. 2024 — doi:10.1007/s40291-024-00731-z
Condition atlasLong COVID Biomarker Atlas

Related Viral markers in Long COVID

Full list: Long COVID Biomarker Atlas.

Frequently asked questions

Is SARS-CoV-2 spike protein high or low in Long COVID?

Mixed. Some studies report higher and others lower SARS-CoV-2 spike protein in Long COVID compared with healthy controls, so no single direction is established. Source: Thomas et al. 2024.

What symptoms is SARS-CoV-2 spike protein associated with in Long COVID?

The cited literature associates this marker with Antigen persistence hypothesis. These are population-level associations and do not mean the marker causes the symptoms.

Which test measures SARS-CoV-2 spike protein?

It is measured as a clinical or physiological test. Many of the cited studies used research-grade assays, so clinical availability may vary.

Is one abnormal SARS-CoV-2 spike protein result diagnostic of Long COVID?

No. No single biomarker is diagnostic of Long COVID. SARS-CoV-2 spike protein 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.

Cite this page

Open Source Medicine Foundation. (2026). SARS-CoV-2 spike protein in Long COVID: direction, evidence and what it means. OSMF Research Tracker. Retrieved October 7, 2026, from https://research.opensourcemed.info/biomarkers/long-covid/sars-cov-2-spike-protein.html
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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.