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

Abstract

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. (c) 2026 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)