COVID Antibody Spectrum Test (CoAST)
for Professionals
The COVID Antibody Spectrum Test (CoAST) is a UKCA-marked multiplex antibody assay, run on our CE-marked Liscar 6 Benchtop Analyser, that quantitatively measures both the quantity and quality of antibody responses to 15 SARS-CoV-2 variants.
Developed by Attomarker Ltd, a spin-out from the University of Exeter, now based in University of Exeter Science Park, the platform and test supports clinicians and researchers in understanding the immune-response heterogeneity seen in Long Covid and post-vaccination immunity.
This page provides resources for clinical interpretation, test performance, and access to publications and datasets related to the COVID Antibody Spectrum Test.
Sections:
- Clinical Use & Interpretation
- Test Performance & Validation
- Publications & Data Access
The Attomarker Long Covid Programme
Attomarker’s research programme investigates immune signatures and viral persistence in patients with Long Covid. Using multiplex antibody profiling, the work has identified distinct immune endotypes that appear to stratify patient responses and symptoms.
Key Observations:
Approximately 60–65% of Long Covid patients display an “immune-gap” endotype, characterised by weak or absent antibody responses to one or more SARS-CoV-2 variants.
Around 10% exhibit a hyper-immune endotype with strong but potentially over-reactive antibody binding and consistent with autoimmune diseases.
The remaining group demonstrate broad, high-quality antibody coverage consistent with effective viral clearance.
These findings suggest that differences in antibody spectrum and quality may explain why some individuals experience prolonged symptoms, while others recover fully. More importantly, in a similar manner to cancer endotypes being critical for personalised treatment choices, these Long COVID endotypes may prove to be equally important in guiding Long COVID treatment and recovery.
Ongoing research focuses on how best to “plug” these immune gaps through targeted vaccination or passive immunisation.
Persistent Virus in Long Covid
The persistence of SARS-CoV-2 components in human tissue is now widely regarded as a significant factor in Long Covid pathophysiology. Multiple studies have reported viral RNA, spike protein, or nucleocapsid antigens in the gut, lymphatic tissue, immune cells, and other organs months after initial infection.
Attomarker’s multiplex data support this model by demonstrating immune gaps consistent with incomplete viral clearance. These data, combined with published evidence from leading research institutions, provide a mechanistic framework linking immune endotype to viral persistence and symptom phenotype.
Summary of evidence:
Viral persistence:
SARS-CoV-2 RNA and proteins identified in post-acute tissues (Chertow et al., Cell, 2022).
Immune dysregulation:
Persistent antigen exposure leading to chronic activation and autoantibody formation (Patterson et al., Front Immunol., 2021).
Endotype stratification:
Attomarker’s longitudinal data show variant-specific antibody deficits in a majority of Long Covid patients (Shaw et al., Attomarker, 2023).
Clinical Use & Interpretation
The CoAST assay provides clinically relevant antibody quantification across multiple SARS-CoV-2 variant antigens. It measures:
Total IgG concentration to spike proteins from multiple variants (including Wuhan, Alpha, Delta, Omicron lineages).
Antibody avidity, a measure of binding quality, derived from competitive binding analysis.
Variant-specific gaps or hyper-responses, forming the basis of immune endotype classification.
Clinical Interpretation Framework
These reservoirs could act as chronic sources of immune activation even after acute infection has resolved.
CoAST reports are intended for use by qualified clinicians. Interpretation should consider:
Reports are accompanied by visual spectrum plots for easy comparison.
Clinicians should integrate results with patient history, symptom profile and additional laboratory findings.
Test Performance & Validation
The CoAST platform has undergone extensive analytical and clinical validation in collaboration with UK research institutions.
Analytical performance highlights
Assay platform:
Attomarker Liscar 6 Multiplex Immunoassay.
Sample type:
Capillary or venous blood.
Dynamic range:
Quantitative across 0.1 – 100 AU for IgG concentration.
Reproducibility:
Coefficient of variation < 10 % across replicate runs.
Cross-reactivity:
Minimal, due to variant-specific spike immobilisation.
Turnaround:
Analysis completed within 10 minutes per run in laboratory settings.
Clinical validation
UKCA marking achieved under ISO 13485:2016 framework.
Detailed validation data and performance reports are available to approved clinical partners.
Publications & Data Access
Attomarker contributes to peer-reviewed research and collaborative studies on Long Covid immunity, endotyping and viral persistence.
Key publications:
Shaw A.M. et al. Identification of Immune Endotypes in Long Covid Using Multiplex Antibody Spectra. Attomarker / University of Exeter (2023).
https://attomarker.com/confronting-long-covid-the-persistent-virus-hypothesis
Chertow D. et al. Persistence of SARS-CoV-2 in Multiple Tissues up to 230 Days after Infection. Cell (2022).
https://www.sciencedirect.com/science/article/pii/S0092867422014266
Zollner A. et al. SARS-CoV-2 Antigen Persistence in the Intestine Is Associated with Ongoing Immune Activation. Gut (2022).
https://gut.bmj.com/content/71/12/2263
Collaboration
Researchers or clinicians seeking to collaborate or analyse anonymised datasets from Attomarker’s Long Covid programme can request access.
Attomarker welcomes collaboration with clinicians, academic groups and research consortia exploring Long Covid, immune profiling or antiviral treatment strategies.