biostudies-literatureUnknown12(2)Li XABSTRACT A prominent aspect of the post-coronavirus disease-2019 (post-COVID-19) era is long-COVID. Therefore, precise patient classification and exploration of the corresponding factors affecting long-COVID are crucial for tailored treatment strategies. Frailty is a common age-related clinical syndrome characterized by deteriorated physiological functions of multiple organ systems, which increases susceptibility to stressors. Herein, we performed an inclusion and exclusion analysis (definite COVID-19 infection diagnosis, clear underlying disease information, ≥60 years old, and repeated sampling of clinical cases) of 10,613 blood samples and identified frailty cases for further investigation. RNA-Seq data were used for differential gene expression and functional and pathway analyses. The rEmerging microbes & infectionshttps://www.ebi.ac.uk/biostudies/studies/S-EPMC10469413biostudies-literatureMast cell activation may contribute to adverse health transitions in COVID-19 patients with frailtyPMC10469413Li XBao ZZhang CfalseMast cell activation may contribute to adverse health transitions in COVID-19 patients with frailtyABSTRACT A prominent aspect of the post-coronavirus disease-2019 (post-COVID-19) era is long-COVID. Therefore, precise patient classification and exploration of the corresponding factors affecting long-COVID are crucial for tailored treatment strategies. Frailty is a common age-related clinical syndrome characterized by deteriorated physiological functions of multiple organ systems, which increases susceptibility to stressors. Herein, we performed an inclusion and exclusion analysis (definite COVID-19 infection diagnosis, clear underlying disease information, ≥60 years old, and repeated sampling of clinical cases) of 10,613 blood samples and identified frailty cases for further investigation. RNA-Seq data were used for differential gene expression and functional and pathway analyses. The r2023-01-01T00:00:00Z2023 Aug2025-04-19T20:08:24.35Z2025-04-19T20:08:24.35ZS-EPMC10469413