• CD4+ and CD8+ T cells were associated with the expression of activation markers (CD38 and HLA-DR), proliferation markers (Ki-67), and exhaustion markers (PD-1).• This elaborate study characterized 200 immune parameters and correlated with clinical features and disease severity.• Increase in chemokines like CXCL10, CXCL9, CCL2, and IL-1RA were observed in half of the COVID-19 patients.• Increased levels of ferritin, D-dimer, and CRP were observed in COVID-19 patients as compared to healthy controls or recovered patients. The gene discussed is CD8A; the disease is COVID-19.