In December 2022, China experienced a significant surge in COVID-19 cases and hospitalizations, particularly among the elderly population. To better understand the immune response in this demographic, researchers from Tianjin Medical University conducted a comprehensive study. Their findings shed light on the immune profile of elderly patients with acute COVID-19 and the potential use of specific cell populations as biomarkers for risk stratification.
During the study, which took place during the United Nations Decade of Healthy Aging, individuals aged ≥ 65 years accounted for 91% of the deaths from COVID-19 in China. The decline and dysregulation of immune function associated with aging, known as immunosenescence, made the elderly more susceptible to severe COVID-19. Lymphopenia, a reduction in the number of lymphocytes, emerged as a key biomarker for severe cases. T cell clonal expansion, necessary for effective anti-viral responses, also showed an age-dependent decline.
The researchers aimed to investigate the immune profile of elderly patients with acute COVID-19 and explore the potential of specific cell populations as biomarkers for risk stratification. They recruited 57 elderly patients and 27 convalescent donors to assess adaptive immunity. The study evaluated binding antibodies, neutralizing antibodies, and T-cell responses among patients with varying levels of COVID-19 severity.
The findings of the study revealed that elderly patients with acute COVID-19 experienced severity-dependent lymphopenia, specifically in CD4+ T cells. The decline in CD4+ T cells correlated with the severity of acute respiratory distress syndrome (ARDS). The study also observed impairment of T follicular helper (Tfh) cell subsets, which play a crucial role in antibody responses. These Tfh subsets were identified as potential biomarkers for risk stratification.
The study considered the broader context of aging and immune function, taking into account convalescent individuals and vaccination as factors influencing immune responses. The decline in Tfh subsets and T follicular regulatory cells (TFR) during acute COVID-19 in the elderly was significant. Correlation analyses revealed associations between these subsets and clinical indicators. Vaccination was found to restore T cell balance and promote robust antibody responses.
These findings have important implications for understanding the immunological dynamics in elderly patients with COVID-19. The decline in Tfh subsets and the potential role of vaccination in mitigating these deficiencies suggest avenues for risk stratification and therapeutic interventions. Tfh-cm emerged as a promising biomarker for assessing the severity status of patients. Vaccination not only addresses acute immune responses but also restores immunophenotypic balance in older adults.
In conclusion, this study highlights the unique immunological challenges faced by the elderly population during the COVID-19 pandemic. Vaccination plays a crucial role in restoring immune balance and should be a focus of public health interventions. Further research is needed to explore the relationship between vaccination history and patient outcomes. The study’s findings have been published on a preprint server and are currently undergoing peer review.