Introduction The long-term clinical burden of Coronavirus disease (COVID-19) remains substantial, yet one-year cohort evidence linking blood-based biomarkers to persistent sequelae is limited. Methods We conducted a longitudinal study in adults aged 18–80 years who were classified as moderate or severe COVID-19 or non-COVID-19 controls. Blood was collected at four time points through 360 days after infection or hospital discharge. Cytokines were quantified by flow cytometry. MMP-2 and MMP-9 leve