CD4 and thymoma: Data indicate that, compared with healthy individuals, patients with GS who have undergone thymoma resection exhibit an increased CD4+/CD8 + T-cell ratio along with a marked reduction in overall T-cell counts in peripheral blood.[22] Effective clearance of SARS-CoV-2 relies heavily on the coordinated actions of CD4 + and CD8 + T-cell subsets.