The study aims to identify clinical profiles of long-COVID patients and correlate them with immunological and molecular data in order to identify prognostic biomarkers and potential therapeutic targets.
Documented SARS-CoV-2 infection
Persistent or complex post-COVID symptoms lasting more than 4 weeks or more than 3 months
Patient referred to the EPSILON pathway or to the post-COVID rehabilitation unit
Age ≥ 18 years
Refusal to participate or to share data
Uncontrolled comorbidities
Pregnant or breastfeeding women
Persons under legal protection or deprived of liberty
his study involves adult patients (≥18 years) with documented SARS-CoV-2 infection referred to a multidisciplinary post-COVID care pathway. Participants present persistent or complex symptoms beyond 4 weeks or 3 months. Recruitment occurs at Hôpital Henry Gabrielle (rehabilitation unit) and Hôpital Lyon Sud (pulmonology department). Patients are enrolled during their regular clinical follow-up. Clinical and biological data are collected at a single inclusion visit.
Cohort
Prospective
Blood sample collection
Other interventionA one-time 30 mL blood draw is performed during the inclusion visit for immunological and molecular analysis as part of the HERVCOV research program. No therapeutic intervention is administered, and no samples are stored after analysis.
Number of participants per clinical cluster at Day 0 (clusters derived from unsupervised multivariate analysis of clinical and paraclinical variables).
At inclusion (Day 0), participants' clinical and paraclinical data will be collected and standardized (z-scores) to derive clinical clusters using unsupervised multivariate methods (principal component analysis for dimensionality reduction if needed, followed by k-means or hierarchical clustering with Euclidean distance).
Differences in clinical and biological parameters between patient subgroups defined by symptom profile and time since initial infection
atients will be classified into subgroups according to the predominant type and severity of post-COVID symptoms (e.g., fatigue-dominant, cognitive, respiratory) and the interval since acute SARS-CoV-2 infection (\<12 months, ≥12 months). Comparative analyses will assess differences in clinical scores (e.g., fatigue, quality of life), and biological markers (e.g., inflammatory cytokines, immune cell subsets) between groups.
Concentration of residual SARS-CoV-2 viral proteins detected in plasma samples at inclusion
Proteomic analyses (e.g., mass spectrometry, immunoassay) will be performed on plasma samples to quantify the presence of SARS-CoV-2 structural or non-structural proteins (e.g., spike, nucleocapsid).
Serum biomarker concentrations at Day 0 by clinical cluster
Blood is collected at inclusion (Day 0). Each analyte concentration (pg/mL or ng/mL, as applicable) will be summarized per cluster as mean (SD) or median (IQR) and compared across clusters using ANOVA or Kruskal-Wallis with post-hoc tests as appropriate; effect sizes and 95% CIs will be reported.
Association between clinical clusters and serum biomarker panel at Day 0 (standardized mean differences and multivariable models)
Cluster membership will be the exposure; each biomarker (standardized) will be the outcome in linear models adjusted for prespecified covariates (e.g., age, sex, time since first SARS-CoV-2 infection). the investigators will report adjusted differences (β) with 95% CIs and p-values; multiplicity will be handled
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