Background: Aging is associated with persistent chronic inflammation and impairment in T cell responses, predisposing severe disease and mortality due to COVID-19 in the acute phase, and a more significant long-term burden of chronic diseases and frailty.

Aims: To identify the association between T cell function and improving or worsening the frailty status at 4 and 12 months of follow-up by assessing cell proliferation and cytokine production.

Methods: A cohort study of 60+ years old individuals (n=15) recruited four months after discharging due to severe COVID-19 and re-assessed at 12 months. Frailty was assessed through FriedŽs phenotype criteria, and T cell subtypes were analyzed using flow cytometry. Two-way ANOVA was performed to detect the association between changes in the frailty status between both assessments and the activation phenotype of T helper cells.

Results: Older adults who worsened their frailty status had a lower proportion of naïve T cells on the first assessment (fig. 1) and more outstanding production of proinflammatory cytokines such as INF-G at one year of follow-up (fig. 2). Patients who improved had lower TNF-a production at four months, less production of the suppressor cytokine IL-10, and a preserved Th1/Th2 proportion on the second assessment.  

Conclusions: COVID-19 older survivors who improve their frailty status at one year of follow-up have a preserved Th1/Th2 phenotype; nevertheless, those who worsen have more outstanding proinflammatory cytokine production.