Static and dynamic scoring systems for post-acute sequelae of SARS-CoV-2 in a Korean Cohort

OBJECTIVES: Persistent symptoms after SARS-CoV-2 infection (PASC, long COVID) remain a major public-health concern. We developed a data-driven definition and static and dynamic PASC scoring systems in a multicenter, prospective-retrospective observational cohort across 12 South Korean institutions. METHODS: Adults enrolled December 2022-March 2025 were followed up to 24 months; 8761 were recruited (7208 infected; 1553 controls) and 4668 met analysis criteria (4388 infected; 280 controls). Using participant-reported symptoms, surveys, and laboratory data, we identified nine symptoms robustly associated with PASC, with anosmia/ageusia and fatigue most influential. RESULTS: A static score integrating indicators observed within 24 months yielded an optimal threshold of 13, classifying 19% of infected participants and 4% of controls as PASC positive. A dynamic score tracking six-month intervals showed symptom burdens peaking at 0-5 months post-infection and declining thereafter; at the same threshold, 33% of infected participants were classified as PASC positive, reflecting temporal fluctuation. CONCLUSION: These data establish a quantitative definition of PASC and introduce a dynamic scoring framework to identify and monitor PASC, supporting future clinical research and practice.