Since the global emergence of SARS-CoV-2 in 2019, the Centers for Disease Control and Prevention (CDC) has recommended an isolation and precaution period of 5 to 10 days for patients with COVID-19, depending on the severity and duration of the symptoms [1]. However, in clinical settings, large proportion of patients show detectable genomic viral copy numbers with occasionally shedding viable virus even after the recommended isolation period. These patients often have multiple underlying diseases, which may contribute to the individual-level heterogeneity of viable virus shedding [2]. Furthermore, the CDC guideline determines the duration of isolation and precaution regardless of vaccination status, despite several studies suggesting shorter viable viral shedding in vaccinated populations [3]. Therefore, an individualized approach is required to determine the isolation period for patients with COVID-19 [2].

The most valid method to evaluate viable virus shedding is culture-based virus isolation [4, 5], which is, however, impractical because of its long running time and high cost [6]. Over the past two years, we conducted four prospective studies to explore the viable virus shedding kinetics of SARS-CoV-2 [3, [7], [8], [9]]. Based on the findings from these early studies, we developed a clinical prediction score system to estimate viable virus shedding, which can contribute to the determination of the isolation and precaution period in real clinical settings.