Second Prospective Cohort of Patients Entering the Multidisciplinary Care Pathway for Post-Covid Syndromes - SyPoCo2 Cohort

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).

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.

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).

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.

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