To the Editor
The decline of T lymphocytes in peripheral blood is a typical laboratory characteristic of patients with COVID-19, especially in severe patients1,2. T-lymphocytes play a critical role in antiviral immunity. CD4+T lymphocyte subsets secretes high level of effector cytokines, especially interferon-γ (IFN-γ), which are essential for virus clearance3. However, there is no research concerning whether CD4+T predicted outcomes of COVID-19 patients.