A study conducted by Jacob K Files et al. and published in The Journal of Clinical Investigation indicated a prolonged period of immune cell dysregulation in hospitalized as well as non-hospitalized SARS-CoV-2-infected patients. The clinical data and samples were procured from hospitalized coronavirus patients (n = 46) and non-hospitalized individuals who had recovered from confirmed coronavirus infection (n = 39). These groups were compared with healthy, coronavirus disease 2019 (COVID-19)-negative controls (n = 20).

In hospitalized subjects, many adaptive and innate immune cells declined in frequency compared to the convalescent and healthy individuals, excluding the rise in B lymphocytes. The outcomes demonstrated raised frequencies of T cell activation markers in subjected admitted to the hospital, with other T cell activation/exhaustion markers remaining higher in non-hospitalized and hospitalized subjects.

In subjects not hospitalized, B cells were found to have a comparable pattern of exhaustion/activation, with elevated frequency of CD69 and CD95 during their stay in hospital. This was followed by the rise in PD1 frequencies. Furthermore, most of these alterations raised over time in non-hospitalized longitudinal samples, demonstrating an extended period of immune dysregulation after coronavirus infection.

The alterations in T cell activation/exhaustion in non-hospitalized subjects were found to be positively correlated with age. Subjects having serious infection displayed a greater expression of activation and exhaustion markers. Additional research exploring immune dysregulation in convalescent individuals is required.