Abstract: -
The SARS-CoV-2 immune response is crucial for disease management,
although diminishing immunity raises the possibility of reinfection. We
examined the immunological response to SARS-CoV-2 in a cohort of
convalescent critically ill COVID-19 patients in matched samples
collected at one month and six to eight months after infection. The
PBMCs were isolated from enrolled study participants and flow cytometry
analysis was done to assess the lymphocyte subsets of naive, effector,
central memory, and effector memory CD4+ or CD8+ T cells in COVID-19
patients at one month and six to eight months after infection.
Immunophenotypic characterization of immune cell subsets was performed
on individuals who were followed longitudinally for one month (n=44) and
up to 6-8 months (n=25) after recovery from COVID infection. We observed
that CD4+ T cells in hospitalized SARS-CoV-2 patients tended to
decrease, whereas CD8+ T cells steadily recovered after one month, while
there was a sustained increase in the population of effector T cells and
effector memory T cells. Furthermore, COVID-19 patients showed
persistently low B cells and a small increase in the NK cell population.
In conclusion, our findings show that T cell responses were maintained
at 6-8 months after infection. This opens new pathways for further
research into the long-term effects in COVID-19 immunopathogenesis.